Merge pull request #12708 from runiq/lsp-doc

Add docs for some methods in vim.lsp

7 files changed, 741 insertions, 135 deletions

diff --git a/runtime/lua/vim/lsp.lua b/runtime/lua/vim/lsp.lua
index 6fe1d15b7e..47dca40208 100644
--- a/runtime/lua/vim/lsp.lua
+++ b/runtime/lua/vim/lsp.lua
@@ -27,11 +27,21 @@ local lsp = {
 
 -- TODO improve handling of scratch buffers with LSP attached.
 
+--@private
+--- Concatenates and writes a list of strings to the Vim error buffer.
+---
+--@param {...} (List of strings) List to write to the buffer
 local function err_message(...)
   nvim_err_writeln(table.concat(vim.tbl_flatten{...}))
   nvim_command("redraw")
 end
 
+--@private
+--- Returns the buffer number for the given {bufnr}.
+---
+--@param bufnr (number) Buffer number to resolve. Defaults to the current
+---buffer if not given.
+--@returns bufnr (number) Number of requested buffer
 local function resolve_bufnr(bufnr)
   validate { bufnr = { bufnr, 'n', true } }
   if bufnr == nil or bufnr == 0 then
@@ -40,6 +50,11 @@ local function resolve_bufnr(bufnr)
   return bufnr
 end
 
+--@private
+--- Checks whether a given path is a directory.
+---
+--@param filename (string) path to check
+--@returns true if {filename} exists and is a directory, false otherwise
 local function is_dir(filename)
   validate{filename={filename,'s'}}
   local stat = uv.fs_stat(filename)
@@ -55,6 +70,10 @@ local valid_encodings = {
 }
 
 local client_index = 0
+--@private
+--- Returns a new, unused client id.
+---
+--@returns (number) client id
 local function next_client_id()
   client_index = client_index + 1
   return client_index
@@ -64,6 +83,12 @@ local active_clients = {}
 local all_buffer_active_clients = {}
 local uninitialized_clients = {}
 
+--@private
+--- Invokes a callback for each LSP client attached to the buffer {bufnr}.
+---
+--@param bufnr (Number) of buffer
+--@param callback (function({client}, {client_id}, {bufnr}) Function to run on
+---each client attached to that buffer.
 local function for_each_buffer_client(bufnr, callback)
   validate {
     callback = { callback, 'f' };
@@ -88,6 +113,11 @@ lsp.client_errors = tbl_extend("error", lsp_rpc.client_errors, vim.tbl_add_rever
   ON_INIT_CALLBACK_ERROR = table.maxn(lsp_rpc.client_errors) + 1;
 })
 
+--@private
+--- Normalizes {encoding} to valid LSP encoding names.
+---
+--@param encoding (string) Encoding to normalize
+--@returns (string) normalized encoding name
 local function validate_encoding(encoding)
   validate {
     encoding = { encoding, 's' };
@@ -96,6 +126,13 @@ local function validate_encoding(encoding)
       or error(string.format("Invalid offset encoding %q. Must be one of: 'utf-8', 'utf-16', 'utf-32'", encoding))
 end
 
+--@internal
+--- Parses a command invocation into the command itself and its args. If there
+--- are no arguments, an empty table is returned as the second argument.
+---
+--@param input (List)
+--@returns (string) the command
+--@returns (list of strings) its arguments
 function lsp._cmd_parts(input)
   vim.validate{cmd={
     input,
@@ -114,12 +151,27 @@ function lsp._cmd_parts(input)
   return cmd, cmd_args
 end
 
+--@private
+--- Augments a validator function with support for optional (nil) values.
+---
+--@param fn (function(v)) The original validator function; should return a
+---bool.
+--@returns (function(v)) The augmented function. Also returns true if {v} is
+---`nil`.
 local function optional_validator(fn)
   return function(v)
     return v == nil or fn(v)
   end
 end
 
+--@private
+--- Validates a client configuration as given to |vim.lsp.start_client()|.
+---
+--@param config (table)
+--@returns (table) "Cleaned" config, containing only the command, its
+---arguments, and a valid encoding.
+---
+--@see |vim.lsp.start_client()|
 local function validate_client_config(config)
   validate {
     config = { config, 't' };
@@ -148,6 +200,11 @@ local function validate_client_config(config)
   }
 end
 
+--@private
+--- Returns full text of buffer {bufnr} as a string.
+---
+--@param bufnr (number) Buffer handle, or 0 for current.
+--@returns Buffer text as string.
 local function buf_get_full_text(bufnr)
   local text = table.concat(nvim_buf_get_lines(bufnr, 0, -1, true), '\n')
   if nvim_buf_get_option(bufnr, 'eol') then
@@ -156,6 +213,11 @@ local function buf_get_full_text(bufnr)
   return text
 end
 
+--@private
+--- Default handler for the 'textDocument/didOpen' LSP notification.
+---
+--@param bufnr (Number) Number of the buffer, or 0 for current
+--@param client Client object
 local function text_document_did_open_handler(bufnr, client)
   if not client.resolved_capabilities.text_document_open_close then
     return
@@ -176,74 +238,90 @@ local function text_document_did_open_handler(bufnr, client)
   util.buf_versions[bufnr] = params.textDocument.version
 end
 
---- LSP client object.
+-- FIXME: DOC: Shouldn't need to use a dummy function
+--
+--- LSP client object. You can get an active client object via
+--- |vim.lsp.get_client_by_id()| or |vim.lsp.get_active_clients()|.
 ---
 --- - Methods:
 ---
----  - request(method, params, [callback])
----     Send a request to the server. If callback is not specified, it will use
----     {client.callbacks} to try to find a callback. If one is not found there,
----     then an error will occur.
+---  - request(method, params, [callback], bufnr)
+---     Sends a request to the server.
 ---     This is a thin wrapper around {client.rpc.request} with some additional
 ---     checking.
----     Returns a boolean to indicate if the notification was successful. If it
----     is false, then it will always be false (the client has shutdown).
----     If it was successful, then it will return the request id as the second
----     result. You can use this with `notify("$/cancel", { id = request_id })`
----     to cancel the request. This helper is made automatically with
----     |vim.lsp.buf_request()|
----     Returns: status, [client_id]
+---     If {callback} is not specified, it will use {client.callbacks} to try to
+---     find a callback. If one is not found there, then an error will occur.
+---     Returns: {status}, {[client_id]}. {status} is a boolean indicating if
+---     the notification was successful. If it is `false`, then it will always
+---     be `false` (the client has shutdown).
+---     If {status} is `true`, the function returns {request_id} as the second
+---     result. You can use this with `client.cancel_request(request_id)`
+---     to cancel the request.
 ---
 ---  - notify(method, params)
----     This is just {client.rpc.notify}()
----     Returns a boolean to indicate if the notification was successful. If it
----     is false, then it will always be false (the client has shutdown).
----     Returns: status
+---     Sends a notification to an LSP server.
+---     Returns: a boolean to indicate if the notification was successful. If
+---     it is false, then it will always be false (the client has shutdown).
 ---
 ---  - cancel_request(id)
----     This is just {client.rpc.notify}("$/cancelRequest", { id = id })
----     Returns the same as `notify()`.
+---     Cancels a request with a given request id.
+---     Returns: same as `notify()`.
 ---
 ---  - stop([force])
----     Stop a client, optionally with force.
+---     Stops a client, optionally with force.
 ---     By default, it will just ask the server to shutdown without force.
 ---     If you request to stop a client which has previously been requested to
 ---     shutdown, it will automatically escalate and force shutdown.
 ---
 ---  - is_stopped()
----     Returns true if the client is fully stopped.
+---     Checks whether a client is stopped.
+---     Returns: true if the client is fully stopped.
+---
+---  - on_attach(bufnr)
+---     Runs the on_attach function from the client's config if it was defined.
 ---
 --- - Members
----  - id (number): The id allocated to the client.
+---  - {id} (number): The id allocated to the client.
 ---
----  - name (string): If a name is specified on creation, that will be
+---  - {name} (string): If a name is specified on creation, that will be
 ---    used. Otherwise it is just the client id. This is used for
 ---    logs and messages.
 ---
----  - offset_encoding (string): The encoding used for communicating
----    with the server. You can modify this in the `on_init` method
+---  - {rpc} (table): RPC client object, for low level interaction with the
+---    client. See |vim.lsp.rpc.start()|.
+---
+---  - {offset_encoding} (string): The encoding used for communicating
+---    with the server. You can modify this in the `config`'s `on_init` method
 ---    before text is sent to the server.
 ---
----  - callbacks (table): The callbacks used by the client as
+---  - {callbacks} (table): The callbacks used by the client as
 ---    described in |lsp-callbacks|.
 ---
----  - config (table): copy of the table that was passed by the user
+---  - {config} (table): copy of the table that was passed by the user
 ---    to |vim.lsp.start_client()|.
 ---
----  - server_capabilities (table): Response from the server sent on
+---  - {server_capabilities} (table): Response from the server sent on
 ---    `initialize` describing the server's capabilities.
 ---
----  - resolved_capabilities (table): Normalized table of
+---  - {resolved_capabilities} (table): Normalized table of
 ---    capabilities that we have detected based on the initialize
 ---    response from the server in `server_capabilities`.
 function lsp.client()
   error()
 end
 
+-- FIXME: DOC: Currently all methods on the `vim.lsp.client` object are
+-- documented twice: Here, and on the methods themselves (e.g.
+-- `client.request()`). This is a workaround for the vimdoc generator script
+-- not handling method names correctly. If you change the documentation on
+-- either, please make sure to update the other as well.
+--
 --- Starts and initializes a client with the given configuration.
 ---
 --- Parameters `cmd` and `root_dir` are required.
 ---
+--- The following parameters describe fields in the {config} table.
+---
 --@param root_dir: (required, string) Directory where the LSP server will base
 --- its rootUri on initialization.
 ---
@@ -271,8 +349,8 @@ end
 ---
 --@param callbacks Map of language server method names to
 --- `function(err, method, params, client_id)` handler. Invoked for:
---- - Notifications from the server, where `err` will always be `nil`.
---- - Requests initiated by the server. For these you can respond by returning
+--- - Notifications to the server, where `err` will always be `nil`.
+--- - Requests by the server. For these you can respond by returning
 ---   two values: `result, err` where err must be shaped like a RPC error,
 ---   i.e. `{ code, message, data? }`. Use |vim.lsp.rpc_response_error()| to
 ---   help with this.
@@ -297,7 +375,7 @@ end
 --@param before_init Callback with parameters (initialize_params, config)
 --- invoked before the LSP "initialize" phase, where `params` contains the
 --- parameters being sent to the server and `config` is the config that was
---- passed to `start_client()`. You can use this to modify parameters before
+--- passed to |vim.lsp.start_client()|. You can use this to modify parameters before
 --- they are sent.
 ---
 --@param on_init Callback (client, initialize_result) invoked after LSP
@@ -335,10 +413,23 @@ function lsp.start_client(config)
 
   local handlers = {}
 
+  --@private
+  --- Returns the callback associated with an LSP method. Returns the default
+  --- callback if the user hasn't set a custom one.
+  ---
+  --@param method (string) LSP method name
+  --@returns (fn) The callback for the given method, if defined, or the default
+  ---from |lsp-callbacks|
   local function resolve_callback(method)
     return callbacks[method] or default_callbacks[method]
   end
 
+  --@private
+  --- Handles a notification sent by an LSP server by invoking the
+  --- corresponding callback.
+  ---
+  --@param method (string) LSP method name
+  --@param params (table) The parameters for that method.
   function handlers.notification(method, params)
     local _ = log.debug() and log.debug('notification', method, params)
     local callback = resolve_callback(method)
@@ -348,6 +439,12 @@ function lsp.start_client(config)
     end
   end
 
+  --@private
+  --- Handles a request from an LSP server by invoking the corresponding
+  --- callback.
+  ---
+  --@param method (string) LSP method name
+  --@param params (table) The parameters for that method
   function handlers.server_request(method, params)
     local _ = log.debug() and log.debug('server_request', method, params)
     local callback = resolve_callback(method)
@@ -359,6 +456,13 @@ function lsp.start_client(config)
     return nil, lsp.rpc_response_error(protocol.ErrorCodes.MethodNotFound)
   end
 
+  --@private
+  --- Invoked when the client operation throws an error.
+  ---
+  --@param code (number) Error code
+  --@param err (...) Other arguments may be passed depending on the error kind
+  --@see |vim.lsp.client_errors| for possible errors. Use
+  ---`vim.lsp.client_errors[code]` to get a human-friendly name.
   function handlers.on_error(code, err)
     local _ = log.error() and log.error(log_prefix, "on_error", { code = lsp.client_errors[code], err = err })
     err_message(log_prefix, ': Error ', lsp.client_errors[code], ': ', vim.inspect(err))
@@ -371,6 +475,11 @@ function lsp.start_client(config)
     end
   end
 
+  --@private
+  --- Invoked on client exit.
+  ---
+  --@param code (number) exit code of the process
+  --@param signal (number) the signal used to terminate (if any)
   function handlers.on_exit(code, signal)
     active_clients[client_id] = nil
     uninitialized_clients[client_id] = nil
@@ -411,6 +520,7 @@ function lsp.start_client(config)
   -- initialize finishes.
   uninitialized_clients[client_id] = client;
 
+  --@private
   local function initialize()
     local valid_traces = {
       off = 'off'; messages = 'messages'; verbose = 'verbose';
@@ -488,6 +598,12 @@ function lsp.start_client(config)
     end)
   end
 
+  --@private
+  --- Throws error for a method that is not supported by the current LSP
+  --- server.
+  ---
+  --@param method (string) an LSP method name not supported by the LSP server.
+  --@returns (error) a 'MethodNotFound' JSON-RPC error response.
   local function unsupported_method(method)
     local msg = "server doesn't support "..method
     local _ = log.warn() and log.warn(msg)
@@ -495,8 +611,28 @@ function lsp.start_client(config)
     return lsp.rpc_response_error(protocol.ErrorCodes.MethodNotFound, msg)
   end
 
-  --- Checks capabilities before rpc.request-ing.
+  --@private
+  --- Sends a request to the server.
+  ---
+  --- This is a thin wrapper around {client.rpc.request} with some additional
+  --- checks for capabilities and callback availability.
+  ---
+  --@param method (string) LSP method name.
+  --@param params (table) LSP request params.
+  --@param callback (function, optional) Response handler for this method.
+  ---If {callback} is not specified, it will use {client.callbacks} to try to
+  ---find a callback. If one is not found there, then an error will occur.
+  --@param bufnr (number) Buffer handle (0 for current).
+  --@returns ({status}, [request_id]): {status} is a bool indicating
+  ---whether the request was successful. If it is `false`, then it will
+  ---always be `false` (the client has shutdown). If it was
+  ---successful, then it will return {request_id} as the
+  ---second result. You can use this with `client.cancel_request(request_id)`
+  ---to cancel the-request.
+  --@see |vim.lsp.buf_request()|
   function client.request(method, params, callback, bufnr)
+    -- FIXME: callback is optional, but bufnr is apparently not? Shouldn't that
+    -- require a `select('#', ...)` call?
     if not callback then
       callback = resolve_callback(method)
         or error(string.format("not found: %q request callback for client %q.", method, client.name))
@@ -521,10 +657,25 @@ function lsp.start_client(config)
     end)
   end
 
+  --@private
+  --- Sends a notification to an LSP server.
+  ---
+  --@param method (string) LSP method name.
+  --@param params (optional, table) LSP request params.
+  --@param bufnr (number) Buffer handle, or 0 for current.
+  --@returns {status} (bool) true if the notification was successful.
+  ---If it is false, then it will always be false
+  ---(the client has shutdown).
   function client.notify(...)
     return rpc.notify(...)
   end
 
+  --@private
+  --- Cancels a request with a given request id.
+  ---
+  --@param id (number) id of request to cancel
+  --@returns true if any client returns true; false otherwise
+  --@see |vim.lsp.client.notify()|
   function client.cancel_request(id)
     validate{id = {id, 'n'}}
     return rpc.notify("$/cancelRequest", { id = id })
@@ -533,6 +684,14 @@ function lsp.start_client(config)
   -- Track this so that we can escalate automatically if we've alredy tried a
   -- graceful shutdown
   local tried_graceful_shutdown = false
+  --@private
+  --- Stops a client, optionally with force.
+  ---
+  ---By default, it will just ask the - server to shutdown without force. If
+  --- you request to stop a client which has previously been requested to
+  --- shutdown, it will automatically escalate and force shutdown.
+  ---
+  --@param force (bool, optional)
   function client.stop(force)
     local handle = rpc.handle
     if handle:is_closing() then
@@ -554,10 +713,18 @@ function lsp.start_client(config)
     end)
   end
 
+  --@private
+  --- Checks whether a client is stopped.
+  ---
+  --@returns (bool) true if client is stopped or in the process of being
+  ---stopped; false otherwise
   function client.is_stopped()
     return rpc.handle:is_closing()
   end
 
+  --@private
+  --- Runs the on_attach function from the client's config if it was defined.
+  --@param bufnr (number) Buffer number
   function client._on_attach(bufnr)
     text_document_did_open_handler(bufnr, client)
     if config.on_attach then
@@ -571,6 +738,12 @@ function lsp.start_client(config)
   return client_id
 end
 
+--@private
+--- Memoizes a function. On first run, the function return value is saved and
+--- immediately returned on subsequent runs.
+---
+--@param fn (function) Function to run
+--@returns (function) Memoized function
 local function once(fn)
   local value
   return function(...)
@@ -579,6 +752,9 @@ local function once(fn)
   end
 end
 
+--@private
+--@fn text_document_did_change_handler(_, bufnr, changedtick, firstline, lastline, new_lastline, old_byte_size, old_utf32_size, old_utf16_size)
+--- Notify all attached clients that a buffer has changed.
 local text_document_did_change_handler
 do
   local encoding_index = { ["utf-8"] = 1; ["utf-16"] = 2; ["utf-32"] = 3; }
@@ -735,7 +911,7 @@ end
 ---
 --@param client_id client id number
 ---
---@return |vim.lsp.client| object, or nil
+--@returns |vim.lsp.client| object, or nil
 function lsp.get_client_by_id(client_id)
   return active_clients[client_id]
 end
@@ -769,7 +945,7 @@ end
 
 --- Gets all active clients.
 ---
---@return Table of |vim.lsp.client| objects
+--@returns Table of |vim.lsp.client| objects
 function lsp.get_active_clients()
   return vim.tbl_values(active_clients)
 end
@@ -904,7 +1080,7 @@ end
 --@param findstart 0 or 1, decides behavior
 --@param base If findstart=0, text to match against
 ---
---@return (number) Decided by `findstart`:
+--@returns (number) Decided by `findstart`:
 --- - findstart=0: column where the completion starts, or -2 or -3
 --- - findstart=1: list of matches (actually just calls |complete()|)
 function lsp.omnifunc(findstart, base)
@@ -948,6 +1124,10 @@ function lsp.omnifunc(findstart, base)
   return -2
 end
 
+---Checks whether a client is stopped.
+---
+--@param client_id (Number)
+--@returns true if client is stopped, false otherwise.
 function lsp.client_is_stopped(client_id)
   return active_clients[client_id] == nil
 end
@@ -992,12 +1172,17 @@ function lsp.set_log_level(level)
 end
 
 --- Gets the path of the logfile used by the LSP client.
+--@returns (String) Path to logfile.
 function lsp.get_log_path()
   return log.get_filename()
 end
 
--- Define the LspDiagnostics signs if they're not defined already.
+-- Defines the LspDiagnostics signs if they're not defined already.
 do
+  --@private
+  --- Defines a sign if it isn't already defined.
+  --@param name (String) Name of the sign
+  --@param properties (table) Properties to attach to the sign
   local function define_default_sign(name, properties)
     if vim.tbl_isempty(vim.fn.sign_getdefined(name)) then
       vim.fn.sign_define(name, properties)
diff --git a/runtime/lua/vim/lsp/buf.lua b/runtime/lua/vim/lsp/buf.lua
index 2e27617997..208082f241 100644
--- a/runtime/lua/vim/lsp/buf.lua
+++ b/runtime/lua/vim/lsp/buf.lua
@@ -7,14 +7,41 @@ local list_extend = vim.list_extend
 
 local M = {}
 
+--@private
+--- Returns nil if {status} is false or nil, otherwise returns the rest of the
+--- arguments.
 local function ok_or_nil(status, ...)
   if not status then return end
   return ...
 end
+
+--@private
+--- Swallows errors.
+---
+--@param fn Function to run
+--@param ... Function arguments
+--@returns Result of `fn(...)` if there are no errors, otherwise nil.
+--- Returns nil if errors occur during {fn}, otherwise returns
 local function npcall(fn, ...)
   return ok_or_nil(pcall(fn, ...))
 end
 
+--@private
+--- Sends an async request to all active clients attached to the current
+--- buffer.
+---
+--@param method (string) LSP method name
+--@param params (optional, table) Parameters to send to the server
+--@param callback (optional, functionnil) Handler
+--  `function(err, method, params, client_id)` for this request. Defaults
+--  to the client callback in `client.callbacks`. See |lsp-callbacks|.
+--
+--@returns 2-tuple:
+---  - Map of client-id:request-id pairs for all successful requests.
+---  - Function which can be used to cancel all the requests. You could instead
+---    iterate all clients and call their `cancel_request()` methods.
+---
+--@see |vim.lsp.buf_request()|
 local function request(method, params, callback)
   validate {
     method = {method, 's'};
@@ -23,9 +50,10 @@ local function request(method, params, callback)
   return vim.lsp.buf_request(0, method, params, callback)
 end
 
---- Sends a notification through all clients associated with current buffer.
---
---@return `true` if server responds.
+--- Checks whether the language servers attached to the current buffer are
+--- ready.
+---
+--@returns `true` if server responds.
 function M.server_ready()
   return not not vim.lsp.buf_notify(0, "window/progress", {})
 end
@@ -74,6 +102,12 @@ end
 
 --- Retrieves the completion items at the current cursor position. Can only be
 --- called in Insert mode.
+---
+--@param context (context support not yet implemented) Additional information
+--- about the context in which a completion was triggered (how it was triggered,
+--- and by which trigger character, if applicable)
+---
+--@see |vim.lsp.protocol.constants.CompletionTriggerKind|
 function M.completion(context)
   local params = util.make_position_params()
   params.context = context
@@ -82,20 +116,27 @@ end
 
 --- Formats the current buffer.
 ---
---- The optional {options} table can be used to specify FormattingOptions, a
---- list of which is available at
---- https://microsoft.github.io/language-server-protocol/specification#textDocument_formatting.
+--@param options (optional, table) Can be used to specify FormattingOptions.
 --- Some unspecified options will be automatically derived from the current
 --- Neovim options.
+--
+--@see https://microsoft.github.io/language-server-protocol/specification#textDocument_formatting
 function M.formatting(options)
   local params = util.make_formatting_params(options)
   return request('textDocument/formatting', params)
 end
 
---- Perform |vim.lsp.buf.formatting()| synchronously.
+--- Performs |vim.lsp.buf.formatting()| synchronously.
 ---
 --- Useful for running on save, to make sure buffer is formatted prior to being
---- saved.  {timeout_ms} is passed on to |vim.lsp.buf_request_sync()|.
+--- saved. {timeout_ms} is passed on to |vim.lsp.buf_request_sync()|. Example:
+---
+--- <pre>
+--- vim.api.nvim_command[[autocmd BufWritePre <buffer> lua vim.lsp.buf.formatting_sync()]]
+--- </pre>
+---
+--@param options Table with valid `FormattingOptions` entries
+--@param timeout_ms (number) Request timeout
 function M.formatting_sync(options, timeout_ms)
   local params = util.make_formatting_params(options)
   local result = vim.lsp.buf_request_sync(0, "textDocument/formatting", params, timeout_ms)
@@ -104,6 +145,13 @@ function M.formatting_sync(options, timeout_ms)
   vim.lsp.util.apply_text_edits(result)
 end
 
+--- Formats a given range.
+---
+--@param options Table with valid `FormattingOptions` entries.
+--@param start_pos ({number, number}, optional) mark-indexed position.
+---Defaults to the start of the last visual selection.
+--@param start_pos ({number, number}, optional) mark-indexed position.
+---Defaults to the end of the last visual selection.
 function M.range_formatting(options, start_pos, end_pos)
   validate {
     options = {options, 't', true};
@@ -138,8 +186,10 @@ function M.range_formatting(options, start_pos, end_pos)
   return request('textDocument/rangeFormatting', params)
 end
 
---- Renames all references to the symbol under the cursor. If {new_name} is not
---- provided, the user will be prompted for a new name using |input()|.
+--- Renames all references to the symbol under the cursor.
+---
+--@param new_name (string) If not provided, the user will be prompted for a new
+---name using |input()|.
 function M.rename(new_name)
   -- TODO(ashkan) use prepareRename
   -- * result: [`Range`](#range) \| `{ range: Range, placeholder: string }` \| `null` describing the range of the string to rename and optionally a placeholder text of the string content to be renamed. If `null` is returned then it is deemed that a 'textDocument/rename' request is not valid at the given position.
@@ -152,6 +202,8 @@ end
 
 --- Lists all the references to the symbol under the cursor in the quickfix window.
 ---
+--@param context (table) Context for the request
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_references
 function M.references(context)
   validate { context = { context, 't', true } }
   local params = util.make_position_params()
@@ -169,6 +221,7 @@ function M.document_symbol()
   request('textDocument/documentSymbol', params)
 end
 
+--@private
 local function pick_call_hierarchy_item(call_hierarchy_items)
   if not call_hierarchy_items then return end
   if #call_hierarchy_items == 1 then
@@ -186,6 +239,9 @@ local function pick_call_hierarchy_item(call_hierarchy_items)
   return choice
 end
 
+--- Lists all the call sites of the symbol under the cursor in the
+--- |quickfix| window. If the symbol can resolve to multiple
+--- items, the user can pick one in the |inputlist|.
 function M.incoming_calls()
   local params = util.make_position_params()
   request('textDocument/prepareCallHierarchy', params, function(_, _, result)
@@ -194,6 +250,9 @@ function M.incoming_calls()
   end)
 end
 
+--- Lists all the items that are called by the symbol under the
+--- cursor in the |quickfix| window. If the symbol can resolve to
+--- multiple items, the user can pick one in the |inputlist|.
 function M.outgoing_calls()
   local params = util.make_position_params()
   request('textDocument/prepareCallHierarchy', params, function(_, _, result)
@@ -204,9 +263,11 @@ end
 
 --- Lists all symbols in the current workspace in the quickfix window.
 ---
---- The list is filtered against the optional argument {query};
---- if the argument is omitted from the call, the user is prompted to enter a string on the command line.
---- An empty string means no filtering is done.
+--- The list is filtered against {query}; if the argument is omitted from the
+--- call, the user is prompted to enter a string on the command line. An empty
+--- string means no filtering is done.
+---
+--@param query (string, optional)
 function M.workspace_symbol(query)
   query = query or npcall(vfn.input, "Query: ")
   local params = {query = query}
@@ -227,10 +288,17 @@ function M.document_highlight()
   request('textDocument/documentHighlight', params)
 end
 
+--- Removes document highlights from current buffer.
+---
 function M.clear_references()
   util.buf_clear_references()
 end
 
+--- Selects a code action from the input list that is available at the current
+--- cursor position.
+--
+--@param context: (table, optional) Valid `CodeActionContext` object
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_codeAction
 function M.code_action(context)
   validate { context = { context, 't', true } }
   context = context or { diagnostics = util.get_line_diagnostics() }
@@ -239,6 +307,10 @@ function M.code_action(context)
   request('textDocument/codeAction', params)
 end
 
+--- Executes an LSP server command.
+---
+--@param command A valid `ExecuteCommandParams` object
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#workspace_executeCommand
 function M.execute_command(command)
   validate {
     command = { command.command, 's' },
diff --git a/runtime/lua/vim/lsp/callbacks.lua b/runtime/lua/vim/lsp/callbacks.lua
index 1ed58995d0..0ee03e6a2f 100644
--- a/runtime/lua/vim/lsp/callbacks.lua
+++ b/runtime/lua/vim/lsp/callbacks.lua
@@ -7,17 +7,24 @@ local buf = require 'vim.lsp.buf'
 
 local M = {}
 
+-- FIXME: DOC: Expose in vimdocs
+
+--@private
+--- Writes to error buffer.
+--@param ... (table of strings) Will be concatenated before being written
 local function err_message(...)
   api.nvim_err_writeln(table.concat(vim.tbl_flatten{...}))
   api.nvim_command("redraw")
 end
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#workspace_executeCommand
 M['workspace/executeCommand'] = function(err, _)
   if err then
     error("Could not execute code action: "..err.message)
   end
 end
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_codeAction
 M['textDocument/codeAction'] = function(_, _, actions)
   if actions == nil or vim.tbl_isempty(actions) then
     print("No code actions available")
@@ -51,6 +58,7 @@ M['textDocument/codeAction'] = function(_, _, actions)
   end
 end
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#workspace_applyEdit
 M['workspace/applyEdit'] = function(_, _, workspace_edit)
   if not workspace_edit then return end
   -- TODO(ashkan) Do something more with label?
@@ -64,6 +72,7 @@ M['workspace/applyEdit'] = function(_, _, workspace_edit)
   }
 end
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_publishDiagnostics
 M['textDocument/publishDiagnostics'] = function(_, _, result)
   if not result then return end
   local uri = result.uri
@@ -102,6 +111,7 @@ M['textDocument/publishDiagnostics'] = function(_, _, result)
   vim.api.nvim_command("doautocmd User LspDiagnosticsChanged")
 end
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_references
 M['textDocument/references'] = function(_, _, result)
   if not result then return end
   util.set_qflist(util.locations_to_items(result))
@@ -109,6 +119,13 @@ M['textDocument/references'] = function(_, _, result)
   api.nvim_command("wincmd p")
 end
 
+--@private
+--- Prints given list of symbols to the quickfix list.
+--@param _ (not used)
+--@param _ (not used)
+--@param result (list of Symbols) LSP method name
+--@param result (table) result of LSP method; a location or a list of locations.
+---(`textDocument/definition` can return `Location` or `Location[]`
 local symbol_callback = function(_, _, result, _, bufnr)
   if not result or vim.tbl_isempty(result) then return end
 
@@ -116,24 +133,30 @@ local symbol_callback = function(_, _, result, _, bufnr)
   api.nvim_command("copen")
   api.nvim_command("wincmd p")
 end
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_documentSymbol
 M['textDocument/documentSymbol'] = symbol_callback
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#workspace_symbol
 M['workspace/symbol'] = symbol_callback
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_rename
 M['textDocument/rename'] = function(_, _, result)
   if not result then return end
   util.apply_workspace_edit(result)
 end
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_rangeFormatting
 M['textDocument/rangeFormatting'] = function(_, _, result)
   if not result then return end
   util.apply_text_edits(result)
 end
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_formatting
 M['textDocument/formatting'] = function(_, _, result)
   if not result then return end
   util.apply_text_edits(result)
 end
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_completion
 M['textDocument/completion'] = function(_, _, result)
   if vim.tbl_isempty(result or {}) then return end
   local row, col = unpack(api.nvim_win_get_cursor(0))
@@ -146,6 +169,7 @@ M['textDocument/completion'] = function(_, _, result)
   vim.fn.complete(textMatch+1, matches)
 end
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_hover
 M['textDocument/hover'] = function(_, method, result)
   util.focusable_float(method, function()
     if not (result and result.contents) then
@@ -166,6 +190,12 @@ M['textDocument/hover'] = function(_, method, result)
   end)
 end
 
+--@private
+--- Jumps to a location. Used as a callback for multiple LSP methods.
+--@param _ (not used)
+--@param method (string) LSP method name
+--@param result (table) result of LSP method; a location or a list of locations.
+---(`textDocument/definition` can return `Location` or `Location[]`
 local function location_callback(_, method, result)
   if result == nil or vim.tbl_isempty(result) then
     local _ = log.info() and log.info(method, 'No location found')
@@ -188,11 +218,16 @@ local function location_callback(_, method, result)
   end
 end
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_declaration
 M['textDocument/declaration'] = location_callback
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_definition
 M['textDocument/definition'] = location_callback
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_typeDefinition
 M['textDocument/typeDefinition'] = location_callback
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_implementation
 M['textDocument/implementation'] = location_callback
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_signatureHelp
 M['textDocument/signatureHelp'] = function(_, method, result)
   util.focusable_preview(method, function()
     if not (result and result.signatures and result.signatures[1]) then
@@ -208,15 +243,21 @@ M['textDocument/signatureHelp'] = function(_, method, result)
   end)
 end
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_documentHighlight
 M['textDocument/documentHighlight'] = function(_, _, result, _)
   if not result then return end
   local bufnr = api.nvim_get_current_buf()
   util.buf_highlight_references(bufnr, result)
 end
 
--- direction is "from" for incoming calls and "to" for outgoing calls
+--@private
+---
+--- Displays call hierarchy in the quickfix window.
+---
+--@param direction `"from"` for incoming calls and `"to"` for outgoing calls
+--@returns `CallHierarchyIncomingCall[]` if {direction} is `"from"`,
+--@returns `CallHierarchyOutgoingCall[]` if {direction} is `"to"`,
 local make_call_hierarchy_callback = function(direction)
-  -- result is a CallHierarchy{Incoming,Outgoing}Call[]
   return function(_, _, result)
     if not result then return end
     local items = {}
@@ -237,10 +278,13 @@ local make_call_hierarchy_callback = function(direction)
   end
 end
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#callHierarchy/incomingCalls
 M['callHierarchy/incomingCalls'] = make_call_hierarchy_callback('from')
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#callHierarchy/outgoingCalls
 M['callHierarchy/outgoingCalls'] = make_call_hierarchy_callback('to')
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#window/logMessage
 M['window/logMessage'] = function(_, _, result, client_id)
   local message_type = result.type
   local message = result.message
@@ -261,6 +305,7 @@ M['window/logMessage'] = function(_, _, result, client_id)
   return result
 end
 
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#window/showMessage
 M['window/showMessage'] = function(_, _, result, client_id)
   local message_type = result.type
   local message = result.message
diff --git a/runtime/lua/vim/lsp/log.lua b/runtime/lua/vim/lsp/log.lua
index 696ce43a59..587a65cd96 100644
--- a/runtime/lua/vim/lsp/log.lua
+++ b/runtime/lua/vim/lsp/log.lua
@@ -2,6 +2,9 @@
 
 local log = {}
 
+-- FIXME: DOC
+-- Should be exposed in the vim docs.
+--
 -- Log level dictionary with reverse lookup as well.
 --
 -- Can be used to lookup the number from the name or the name from the number.
@@ -21,12 +24,14 @@ local log_date_format = "%FT%H:%M:%S%z"
 
 do
   local path_sep = vim.loop.os_uname().sysname == "Windows" and "\\" or "/"
+  --@private
   local function path_join(...)
     return table.concat(vim.tbl_flatten{...}, path_sep)
   end
   local logfilename = path_join(vim.fn.stdpath('data'), 'lsp.log')
 
-  --- Return the log filename.
+  --- Returns the log filename.
+  --@returns (string) log filename
   function log.get_filename()
     return logfilename
   end
@@ -36,6 +41,9 @@ do
   for level, levelnr in pairs(log.levels) do
     -- Also export the log level on the root object.
     log[level] = levelnr
+    -- FIXME: DOC
+    -- Should be exposed in the vim docs.
+    --
     -- Set the lowercase name as the main use function.
     -- If called without arguments, it will check whether the log level is
     -- greater than or equal to this one. When called with arguments, it will
@@ -74,6 +82,8 @@ end
 -- interfere with iterating the levels
 vim.tbl_add_reverse_lookup(log.levels)
 
+--- Sets the current log level.
+--@param level (string or number) One of `vim.lsp.log.levels`
 function log.set_level(level)
   if type(level) == 'string' then
     current_log_level = assert(log.levels[level:upper()], string.format("Invalid log level: %q", level))
@@ -84,8 +94,9 @@ function log.set_level(level)
   end
 end
 
--- Return whether the level is sufficient for logging.
--- @param level number log level
+--- Checks whether the level is sufficient for logging.
+--@param level number log level
+--@returns (bool) true if would log, false if not
 function log.should_log(level)
   return level >= current_log_level
 end
diff --git a/runtime/lua/vim/lsp/protocol.lua b/runtime/lua/vim/lsp/protocol.lua
index ef5e08680e..4e926381e0 100644
--- a/runtime/lua/vim/lsp/protocol.lua
+++ b/runtime/lua/vim/lsp/protocol.lua
@@ -2,6 +2,11 @@
 
 local protocol = {}
 
+--@private
+--- Returns {a} if it is not nil, otherwise returns {b}.
+---
+--@param a
+--@param b
 local function ifnil(a, b)
   if a == nil then return b end
   return a
@@ -9,12 +14,14 @@ end
 
 
 --[=[
--- Useful for interfacing with:
--- https://github.com/microsoft/language-server-protocol/raw/gh-pages/_specifications/specification-3-14.md
+--@private
+--- Useful for interfacing with:
+--- https://github.com/microsoft/language-server-protocol/raw/gh-pages/_specifications/specification-3-14.md
 function transform_schema_comments()
   nvim.command [[silent! '<,'>g/\/\*\*\|\*\/\|^$/d]]
   nvim.command [[silent! '<,'>s/^\(\s*\) \* \=\(.*\)/\1--\2/]]
 end
+--@private
 function transform_schema_to_table()
   transform_schema_comments()
   nvim.command [[silent! '<,'>s/: \S\+//]]
diff --git a/runtime/lua/vim/lsp/rpc.lua b/runtime/lua/vim/lsp/rpc.lua
index 81c92bfe05..680e1ba6ae 100644
--- a/runtime/lua/vim/lsp/rpc.lua
+++ b/runtime/lua/vim/lsp/rpc.lua
@@ -5,6 +5,11 @@ local protocol = require('vim.lsp.protocol')
 local validate, schedule, schedule_wrap = vim.validate, vim.schedule, vim.schedule_wrap
 
 -- TODO replace with a better implementation.
+--@private
+--- Encodes to JSON.
+---
+--@param data (table) Data to encode
+--@returns (string) Encoded object
 local function json_encode(data)
   local status, result = pcall(vim.fn.json_encode, data)
   if status then
@@ -13,6 +18,11 @@ local function json_encode(data)
     return nil, result
   end
 end
+--@private
+--- Decodes from JSON.
+---
+--@param data (string) Data to decode
+--@returns (table) Decoded JSON object
 local function json_decode(data)
   local status, result = pcall(vim.fn.json_decode, data)
   if status then
@@ -22,17 +32,26 @@ local function json_decode(data)
   end
 end
 
+--@private
+--- Checks whether a given path exists and is a directory.
+--@param filename (string) path to check
+--@returns (bool)
 local function is_dir(filename)
   local stat = vim.loop.fs_stat(filename)
   return stat and stat.type == 'directory' or false
 end
 
 local NIL = vim.NIL
+--@private
+--- Returns its argument, but converts `vim.NIL` to Lua `nil`.
+--@param v (any) Argument
+--@returns (any)
 local function convert_NIL(v)
   if v == NIL then return nil end
   return v
 end
 
+--@private
 --- Merges current process env with the given env and returns the result as
 --- a list of "k=v" strings.
 ---
@@ -42,6 +61,8 @@ end
 ---  in:    { PRODUCTION="false", PATH="/usr/bin/", PORT=123, HOST="0.0.0.0", }
 ---  out:   { "PRODUCTION=false", "PATH=/usr/bin/", "PORT=123", "HOST=0.0.0.0", }
 --- </pre>
+--@param env (table) table of environment variable assignments
+--@returns (table) list of `"k=v"` strings
 local function env_merge(env)
   if env == nil then
     return env
@@ -56,6 +77,11 @@ local function env_merge(env)
   return final_env
 end
 
+--@private
+--- Embeds the given string into a table and correctly computes `Content-Length`.
+---
+--@param encoded_message (string)
+--@returns (table) table containing encoded message and `Content-Length` attribute
 local function format_message_with_content_length(encoded_message)
   return table.concat {
     'Content-Length: '; tostring(#encoded_message); '\r\n\r\n';
@@ -63,8 +89,11 @@ local function format_message_with_content_length(encoded_message)
   }
 end
 
---- Parse an LSP Message's header
--- @param header: The header to parse.
+--@private
+--- Parses an LSP Message's header
+---
+--@param header: The header to parse.
+--@returns Parsed headers
 local function parse_headers(header)
   if type(header) ~= 'string' then
     return nil
@@ -92,6 +121,8 @@ end
 -- case insensitive pattern.
 local header_start_pattern = ("content"):gsub("%w", function(c) return "["..c..c:upper().."]" end)
 
+--@private
+--- The actual workhorse.
 local function request_parser_loop()
   local buffer = ''
   while true do
@@ -138,6 +169,10 @@ local client_errors = vim.tbl_add_reverse_lookup {
   SERVER_RESULT_CALLBACK_ERROR = 7;
 }
 
+--- Constructs an error message from an LSP error object.
+---
+--@param err (table) The error object
+--@returns (string) The formatted error message
 local function format_rpc_error(err)
   validate {
     err = { err, 't' };
@@ -182,23 +217,69 @@ local function rpc_response_error(code, message, data)
 end
 
 local default_handlers = {}
+--@private
+--- Default handler for notifications sent to an LSP server.
+---
+--@param method (string) The invoked LSP method
+--@param params (table): Parameters for the invoked LSP method
 function default_handlers.notification(method, params)
   local _ = log.debug() and log.debug('notification', method, params)
 end
+--@private
+--- Default handler for requests sent to an LSP server.
+---
+--@param method (string) The invoked LSP method
+--@param params (table): Parameters for the invoked LSP method
+--@returns `nil` and `vim.lsp.protocol.ErrorCodes.MethodNotFound`.
 function default_handlers.server_request(method, params)
   local _ = log.debug() and log.debug('server_request', method, params)
   return nil, rpc_response_error(protocol.ErrorCodes.MethodNotFound)
 end
+--@private
+--- Default handler for when a client exits.
+---
+--@param code (number): Exit code
+--@param signal (number): Number describing the signal used to terminate (if
+---any)
 function default_handlers.on_exit(code, signal)
-  local _ = log.info() and log.info("client exit", { code = code, signal = signal })
+  local _ = log.info() and log.info("client_exit", { code = code, signal = signal })
 end
+--@private
+--- Default handler for client errors.
+---
+--@param code (number): Error code
+--@param err (any): Details about the error
+---any)
 function default_handlers.on_error(code, err)
   local _ = log.error() and log.error('client_error:', client_errors[code], err)
 end
 
---- Create and start an RPC client.
--- @param cmd [
-local function create_and_start_client(cmd, cmd_args, handlers, extra_spawn_params)
+--- Starts an LSP server process and create an LSP RPC client object to
+--- interact with it.
+---
+--@param cmd (string) Command to start the LSP server.
+--@param cmd_args (table) List of additional string arguments to pass to {cmd}.
+--@param handlers (table, optional) Handlers for LSP message types. Valid
+---handler names are:
+--- - `"notification"`
+--- - `"server_request"`
+--- - `"on_error"`
+--- - `"on_exit"`
+--@param extra_spawn_params (table, optional) Additional context for the LSP
+--- server process. May contain:
+--- - {cwd} (string) Working directory for the LSP server process
+--- - {env} (table) Additional environment variables for LSP server process
+--@returns Client RPC object.
+---
+--@returns Methods:
+--- - `notify()` |vim.lsp.rpc.notify()|
+--- - `request()` |vim.lsp.rpc.request()|
+---
+--@returns Members:
+--- - {pid} (number) The LSP server's PID.
+--- - {handle} A handle for low-level interaction with the LSP server process
+---   |vim.loop|.
+local function start(cmd, cmd_args, handlers, extra_spawn_params)
   local _ = log.info() and log.info("Starting RPC client", {cmd = cmd, args = cmd_args, extra = extra_spawn_params})
   validate {
     cmd = { cmd, 's' };
@@ -242,6 +323,11 @@ local function create_and_start_client(cmd, cmd_args, handlers, extra_spawn_para
 
   local handle, pid
   do
+    --@private
+    --- Callback for |vim.loop.spawn()| Closes all streams and runs the
+    --- `on_exit` handler.
+    --@param code (number) Exit code
+    --@param signal (number) Signal that was used to terminate (if any)
     local function onexit(code, signal)
       stdin:close()
       stdout:close()
@@ -265,6 +351,12 @@ local function create_and_start_client(cmd, cmd_args, handlers, extra_spawn_para
     handle, pid = uv.spawn(cmd, spawn_params, onexit)
   end
 
+  --@private
+  --- Encodes {payload} into a JSON-RPC message and sends it to the remote
+  --- process.
+  ---
+  --@param payload (table) Converted into a JSON string, see |json_encode()|
+  --@returns true if the payload could be scheduled, false if the main event-loop is in the process of closing.
   local function encode_and_send(payload)
     local _ = log.debug() and log.debug("rpc.send.payload", payload)
     if handle:is_closing() then return false end
@@ -276,7 +368,14 @@ local function create_and_start_client(cmd, cmd_args, handlers, extra_spawn_para
     return true
   end
 
-  local function send_notification(method, params)
+  -- FIXME: DOC: Should be placed on the RPC client object returned by
+  -- `start()`
+  --
+  --- Sends a notification to the LSP server.
+  --@param method (string) The invoked LSP method
+  --@param params (table): Parameters for the invoked LSP method
+  --@returns (bool) `true` if notification could be sent, `false` if not
+  local function notify(method, params)
     local _ = log.debug() and log.debug("rpc.notify", method, params)
     return encode_and_send {
       jsonrpc = "2.0";
@@ -285,6 +384,8 @@ local function create_and_start_client(cmd, cmd_args, handlers, extra_spawn_para
     }
   end
 
+  --@private
+  --- sends an error object to the remote LSP process.
   local function send_response(request_id, err, result)
     return encode_and_send {
       id = request_id;
@@ -294,7 +395,16 @@ local function create_and_start_client(cmd, cmd_args, handlers, extra_spawn_para
     }
   end
 
-  local function send_request(method, params, callback)
+  -- FIXME: DOC: Should be placed on the RPC client object returned by
+  -- `start()`
+  --
+  --- Sends a request to the LSP server and runs {callback} upon response.
+  ---
+  --@param method (string) The invoked LSP method
+  --@param params (table) Parameters for the invoked LSP method
+  --@param callback (function) Callback to invoke
+  --@returns (bool, number) `(true, message_id)` if request could be sent, `false` if not
+  local function request(method, params, callback)
     validate {
       callback = { callback, 'f' };
     }
@@ -320,11 +430,13 @@ local function create_and_start_client(cmd, cmd_args, handlers, extra_spawn_para
     end
   end)
 
+  --@private
   local function on_error(errkind, ...)
     assert(client_errors[errkind])
     -- TODO what to do if this fails?
     pcall(handlers.on_error, errkind, ...)
   end
+  --@private
   local function pcall_handler(errkind, status, head, ...)
     if not status then
       on_error(errkind, head, ...)
@@ -332,6 +444,7 @@ local function create_and_start_client(cmd, cmd_args, handlers, extra_spawn_para
     end
     return status, head, ...
   end
+  --@private
   local function try_call(errkind, fn, ...)
     return pcall_handler(errkind, pcall(fn, ...))
   end
@@ -340,6 +453,7 @@ local function create_and_start_client(cmd, cmd_args, handlers, extra_spawn_para
   -- time and log them. This would require storing the timestamp. I could call
   -- them with an error then, perhaps.
 
+  --@private
   local function handle_body(body)
     local decoded, err = json_decode(body)
     if not decoded then
@@ -458,13 +572,13 @@ local function create_and_start_client(cmd, cmd_args, handlers, extra_spawn_para
   return {
     pid = pid;
     handle = handle;
-    request = send_request;
-    notify = send_notification;
+    request = request;
+    notify = notify
   }
 end
 
 return {
-  start = create_and_start_client;
+  start = start;
   rpc_response_error = rpc_response_error;
   format_rpc_error = format_rpc_error;
   client_errors = client_errors;
diff --git a/runtime/lua/vim/lsp/util.lua b/runtime/lua/vim/lsp/util.lua
index 33fca29ecd..3ec7311d65 100644
--- a/runtime/lua/vim/lsp/util.lua
+++ b/runtime/lua/vim/lsp/util.lua
@@ -7,6 +7,7 @@ local highlight = require 'vim.highlight'
 
 local M = {}
 
+-- FIXME: DOC: Expose in vimdocs
 --- Diagnostics received from the server via `textDocument/publishDiagnostics`
 -- by buffer.
 --
@@ -33,18 +34,30 @@ local M = {}
 M.diagnostics_by_buf = {}
 
 local split = vim.split
+--@private
 local function split_lines(value)
   return split(value, '\n', true)
 end
 
+--@private
 local function ok_or_nil(status, ...)
   if not status then return end
   return ...
 end
+--@private
 local function npcall(fn, ...)
   return ok_or_nil(pcall(fn, ...))
 end
 
+--- Replaces text in a range with new text.
+---
+--- CAUTION: Changes in-place!
+---
+--@param lines (table) Original list of strings
+--@param A (table) Start position; a 2-tuple of {line, col} numbers
+--@param B (table) End position; a 2-tuple of {line, col} numbers
+--@param new_lines A list of strings to replace the original
+--@returns (table) The modified {lines} object
 function M.set_lines(lines, A, B, new_lines)
   -- 0-indexing to 1-indexing
   local i_0 = A[1] + 1
@@ -78,6 +91,7 @@ function M.set_lines(lines, A, B, new_lines)
   return lines
 end
 
+--@private
 local function sort_by_key(fn)
   return function(a,b)
     local ka, kb = fn(a), fn(b)
@@ -91,13 +105,15 @@ local function sort_by_key(fn)
     return false
   end
 end
+--@private
 local edit_sort_key = sort_by_key(function(e)
   return {e.A[1], e.A[2], e.i}
 end)
 
+--@private
 --- Position is a https://microsoft.github.io/language-server-protocol/specifications/specification-current/#position
--- Returns a zero-indexed column, since set_lines() does the conversion to
--- 1-indexed
+--- Returns a zero-indexed column, since set_lines() does the conversion to
+--- 1-indexed
 local function get_line_byte_from_position(bufnr, position)
   -- LSP's line and characters are 0-indexed
   -- Vim's line and columns are 1-indexed
@@ -114,6 +130,9 @@ local function get_line_byte_from_position(bufnr, position)
   return col
 end
 
+--- Applies a list of text edits to a buffer.
+--@param text_edits (table) list of `TextEdit` objects
+--@param buf_nr (number) Buffer id
 function M.apply_text_edits(text_edits, bufnr)
   if not next(text_edits) then return end
   if not api.nvim_buf_is_loaded(bufnr) then
@@ -168,20 +187,30 @@ end
 -- function M.glob_to_regex(glob)
 -- end
 
--- textDocument/completion response returns one of CompletionItem[], CompletionList or null.
--- https://microsoft.github.io/language-server-protocol/specification#textDocument_completion
+--- Can be used to extract the completion items from a
+--- `textDocument/completion` request, which may return one of
+--- `CompletionItem[]`, `CompletionList` or null.
+--@param result (table) The result of a `textDocument/completion` request
+--@returns (table) List of completion items
+--@see https://microsoft.github.io/language-server-protocol/specification#textDocument_completion
 function M.extract_completion_items(result)
   if type(result) == 'table' and result.items then
+    -- result is a `CompletionList`
     return result.items
   elseif result ~= nil then
+    -- result is `CompletionItem[]`
     return result
   else
+    -- result is `null`
     return {}
   end
 end
 
---- Apply the TextDocumentEdit response.
--- @params TextDocumentEdit [table] see https://microsoft.github.io/language-server-protocol/specification
+--- Applies a `TextDocumentEdit`, which is a list of changes to a single
+-- document.
+---
+--@param text_document_edit (table) a `TextDocumentEdit` object
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocumentEdit
 function M.apply_text_document_edit(text_document_edit)
   local text_document = text_document_edit.textDocument
   local bufnr = vim.uri_to_bufnr(text_document.uri)
@@ -195,6 +224,13 @@ function M.apply_text_document_edit(text_document_edit)
   M.apply_text_edits(text_document_edit.edits, bufnr)
 end
 
+--@private
+--- Recursively parses snippets in a completion entry.
+---
+--@param input (string) Snippet text to parse for snippets
+--@param inner (bool) Whether this function is being called recursively
+--@returns 2-tuple of strings: The first is the parsed result, the second is the
+---unparsed rest of the input
 local function parse_snippet_rec(input, inner)
   local res = ""
 
@@ -248,15 +284,20 @@ local function parse_snippet_rec(input, inner)
   return res, input
 end
 
--- Parse completion entries, consuming snippet tokens
+--- Parses snippets in a completion entry.
+---
+--@param input (string) unparsed snippet
+--@returns (string) parsed snippet
 function M.parse_snippet(input)
   local res, _ = parse_snippet_rec(input, false)
 
   return res
 end
 
--- Sort by CompletionItem.sortText
--- https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_completion
+--@private
+--- Sorts by CompletionItem.sortText.
+---
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_completion
 local function sort_completion_items(items)
   if items[1] and items[1].sortText then
     table.sort(items, function(a, b) return a.sortText < b.sortText
@@ -264,9 +305,10 @@ local function sort_completion_items(items)
   end
 end
 
--- Returns text that should be inserted when selecting completion item. The precedence is as follows:
--- textEdit.newText > insertText > label
--- https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_completion
+--@private
+--- Returns text that should be inserted when selecting completion item. The
+--- precedence is as follows: textEdit.newText > insertText > label
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_completion
 local function get_completion_word(item)
   if item.textEdit ~= nil and item.textEdit.newText ~= nil then
     if protocol.InsertTextFormat[item.insertTextFormat] == "PlainText" then
@@ -284,8 +326,10 @@ local function get_completion_word(item)
   return item.label
 end
 
--- Some language servers return complementary candidates whose prefixes do not match are also returned.
--- So we exclude completion candidates whose prefix does not match.
+--@private
+--- Some language servers return complementary candidates whose prefixes do not
+--- match are also returned. So we exclude completion candidates whose prefix
+--- does not match.
 local function remove_unmatch_completion_items(items, prefix)
   return vim.tbl_filter(function(item)
     local word = get_completion_word(item)
@@ -293,16 +337,26 @@ local function remove_unmatch_completion_items(items, prefix)
   end, items)
 end
 
--- Acording to LSP spec, if the client set "completionItemKind.valueSet",
--- the client must handle it properly even if it receives a value outside the specification.
--- https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_completion
+--- Acording to LSP spec, if the client set `completionItemKind.valueSet`,
+--- the client must handle it properly even if it receives a value outside the
+--- specification.
+---
+--@param completion_item_kind (`vim.lsp.protocol.completionItemKind`)
+--@returns (`vim.lsp.protocol.completionItemKind`)
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_completion
 function M._get_completion_item_kind_name(completion_item_kind)
   return protocol.CompletionItemKind[completion_item_kind] or "Unknown"
 end
 
---- Getting vim complete-items with incomplete flag.
--- @params CompletionItem[], CompletionList or nil (https://microsoft.github.io/language-server-protocol/specification#textDocument_completion)
--- @return { matches = complete-items table, incomplete = boolean  }
+--- Turns the result of a `textDocument/completion` request into vim-compatible
+--- |complete-items|.
+---
+--@param result The result of a `textDocument/completion` call, e.g. from
+---|vim.lsp.buf.completion()|, which may be one of `CompletionItem[]`,
+--- `CompletionList` or `null`
+--@param prefix (string) the prefix to filter the completion items
+--@returns { matches = complete-items table, incomplete = bool }
+--@see |complete-items|
 function M.text_document_completion_list_to_complete_items(result, prefix)
   local items = M.extract_completion_items(result)
   if vim.tbl_isempty(items) then
@@ -350,7 +404,10 @@ function M.text_document_completion_list_to_complete_items(result, prefix)
   return matches
 end
 
--- @params WorkspaceEdit [table] see https://microsoft.github.io/language-server-protocol/specification
+--- Applies a `WorkspaceEdit`.
+---
+--@param workspace_edit (table) `WorkspaceEdit`
+-- @see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#workspace_applyEdit
 function M.apply_workspace_edit(workspace_edit)
   if workspace_edit.documentChanges then
     for _, change in ipairs(workspace_edit.documentChanges) do
@@ -375,9 +432,15 @@ function M.apply_workspace_edit(workspace_edit)
   end
 end
 
---- Convert any of MarkedString | MarkedString[] | MarkupContent into markdown text lines
--- see https://microsoft.github.io/language-server-protocol/specifications/specification-3-14/#textDocument_hover
--- Useful for textDocument/hover, textDocument/signatureHelp, and potentially others.
+--- Converts any of `MarkedString` | `MarkedString[]` | `MarkupContent` into
+--- a list of lines containing valid markdown. Useful to populate the hover
+--- window for `textDocument/hover`, for parsing the result of
+--- `textDocument/signatureHelp`, and potentially others.
+---
+--@param input (`MarkedString` | `MarkedString[]` | `MarkupContent`)
+--@param contents (table, optional, default `{}`) List of strings to extend with converted lines
+--@returns {contents}, extended with lines of converted markdown.
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_hover
 function M.convert_input_to_markdown_lines(input, contents)
   contents = contents or {}
   -- MarkedString variation 1
@@ -416,8 +479,11 @@ function M.convert_input_to_markdown_lines(input, contents)
   return contents
 end
 
---- Convert SignatureHelp response to markdown lines.
--- https://microsoft.github.io/language-server-protocol/specifications/specification-3-14/#textDocument_signatureHelp
+--- Converts `textDocument/SignatureHelp` response to markdown lines.
+---
+--@param signature_help Response of `textDocument/SignatureHelp`
+--@returns list of lines of converted markdown.
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_signatureHelp
 function M.convert_signature_help_to_markdown_lines(signature_help)
   if not signature_help.signatures then
     return
@@ -475,6 +541,13 @@ function M.convert_signature_help_to_markdown_lines(signature_help)
   return contents
 end
 
+--- Creates a table with sensible default options for a floating window. The
+--- table can be passed to |nvim_open_win()|.
+---
+--@param width (number) window width (in character cells)
+--@param height (number) window height (in character cells)
+--@param opts (table, optional)
+--@returns (table) Options
 function M.make_floating_popup_options(width, height, opts)
   validate {
     opts = { opts, 't', true };
@@ -520,6 +593,10 @@ function M.make_floating_popup_options(width, height, opts)
   }
 end
 
+--- Jumps to a location.
+---
+--@param location (`Location`|`LocationLink`)
+--@returns `true` if the jump succeeded
 function M.jump_to_location(location)
   -- location may be Location or LocationLink
   local uri = location.uri or location.targetUri
@@ -543,14 +620,14 @@ function M.jump_to_location(location)
   return true
 end
 
---- Preview a location in a floating windows
+--- Previews a location in a floating window
 ---
 --- behavior depends on type of location:
 ---   - for Location, range is shown (e.g., function definition)
 ---   - for LocationLink, targetRange is shown (e.g., body of function definition)
 ---
---@param location a single Location or LocationLink
---@return bufnr,winnr buffer and window number of floating window or nil
+--@param location a single `Location` or `LocationLink`
+--@returns (bufnr,winnr) buffer and window number of floating window or nil
 function M.preview_location(location)
   -- location may be LocationLink or Location (more useful for the former)
   local uri = location.targetUri or location.uri
@@ -565,6 +642,7 @@ function M.preview_location(location)
   return M.open_floating_preview(contents, filetype)
 end
 
+--@private
 local function find_window_by_var(name, value)
   for _, win in ipairs(api.nvim_list_wins()) do
     if npcall(api.nvim_win_get_var, win, name) == value then
@@ -573,12 +651,18 @@ local function find_window_by_var(name, value)
   end
 end
 
--- Check if a window with `unique_name` tagged is associated with the current
--- buffer. If not, make a new preview.
---
--- fn()'s return bufnr, winnr
--- case that a new floating window should be created.
+--- Enters/leaves the focusable window associated with the current buffer via the
+--window - variable `unique_name`. If no such window exists, run the function
+--{fn}.
+---
+--@param unique_name (string) Window variable
+--@param fn (function) should return create a new window and return a tuple of
+---({focusable_buffer_id}, {window_id}). if {focusable_buffer_id} is a valid
+---buffer id, the newly created window will be the new focus associated with
+---the current buffer via the tag `unique_name`.
+--@returns (pbufnr, pwinnr) if `fn()` has created a new window; nil otherwise
 function M.focusable_float(unique_name, fn)
+  -- Go back to previous window if we are in a focusable one
   if npcall(api.nvim_win_get_var, 0, unique_name) then
     return api.nvim_command("wincmd p")
   end
@@ -598,18 +682,21 @@ function M.focusable_float(unique_name, fn)
   end
 end
 
--- Check if a window with `unique_name` tagged is associated with the current
--- buffer. If not, make a new preview.
---
--- fn()'s return values will be passed directly to open_floating_preview in the
--- case that a new floating window should be created.
+--- Focuses/unfocuses the floating preview window associated with the current
+--- buffer via the window variable `unique_name`. If no such preview window
+--- exists, makes a new one.
+---
+--@param unique_name (string) Window variable
+--@param fn (function) The return values of this function will be passed
+---directly to |vim.lsp.util.open_floating_preview()|, in the case that a new
+---floating window should be created
 function M.focusable_preview(unique_name, fn)
   return M.focusable_float(unique_name, function()
     return M.open_floating_preview(fn())
   end)
 end
 
---- Trim empty lines from input and pad left and right with spaces
+--- Trims empty lines from input and pad left and right with spaces
 ---
 --@param contents table of lines to trim and pad
 --@param opts dictionary with optional fields
@@ -617,7 +704,7 @@ end
 --             - pad_right  number of columns to pad contents at right (default 1)
 --             - pad_top    number of lines to pad contents at top (default 0)
 --             - pad_bottom number of lines to pad contents at bottom (default 0)
---@return contents table of trimmed and padded lines
+--@returns contents table of trimmed and padded lines
 function M._trim_and_pad(contents, opts)
   validate {
     contents = { contents, 't' };
@@ -645,12 +732,13 @@ end
 
 
 
---- Convert markdown into syntax highlighted regions by stripping the code
+-- TODO: refactor to separate stripping/converting and make use of open_floating_preview
+--
+--- Converts markdown into syntax highlighted regions by stripping the code
 --- blocks and converting them into highlighted code.
 --- This will by default insert a blank line separator after those code block
 --- regions to improve readability.
---- The result is shown in a floating preview
---- TODO: refactor to separate stripping/converting and make use of open_floating_preview
+--- The result is shown in a floating preview.
 ---
 --@param contents table of lines to show in window
 --@param opts dictionary with optional fields
@@ -664,7 +752,7 @@ end
 --             - pad_top    number of lines to pad contents at top
 --             - pad_bottom number of lines to pad contents at bottom
 --             - separator insert separator after code block
---@return width,height size of float
+--@returns width,height size of float
 function M.fancy_floating_markdown(contents, opts)
   validate {
     contents = { contents, 't' };
@@ -738,6 +826,7 @@ function M.fancy_floating_markdown(contents, opts)
 
   vim.cmd("ownsyntax markdown")
   local idx = 1
+  --@private
   local function apply_syntax_to_region(ft, start, finish)
     if ft == '' then return end
     local name = ft..idx
@@ -763,11 +852,17 @@ function M.fancy_floating_markdown(contents, opts)
   return bufnr, winnr
 end
 
+--- Creates autocommands to close a preview window when events happen.
+---
+--@param events (table) list of events
+--@param winnr (number) window id of preview window
+--@see |autocmd-events|
 function M.close_preview_autocmd(events, winnr)
   api.nvim_command("autocmd "..table.concat(events, ',').." <buffer> ++once lua pcall(vim.api.nvim_win_close, "..winnr..", true)")
 end
 
---- Compute size of float needed to show contents (with optional wrapping)
+--@internal
+--- Computes size of float needed to show contents (with optional wrapping)
 ---
 --@param contents table of lines to show in window
 --@param opts dictionary with optional fields
@@ -776,7 +871,7 @@ end
 --             - wrap_at character to wrap at for computing height
 --             - max_width  maximal width of floating window
 --             - max_height maximal height of floating window
---@return width,height size of float
+--@returns width,height size of float
 function M._make_floating_popup_size(contents, opts)
   validate {
     contents = { contents, 't' };
@@ -827,7 +922,7 @@ function M._make_floating_popup_size(contents, opts)
   return width, height
 end
 
---- Show contents in a floating window
+--- Shows contents in a floating window.
 ---
 --@param contents table of lines to show in window
 --@param filetype string of filetype to set for opened buffer
@@ -841,7 +936,8 @@ end
 --             - pad_right  number of columns to pad contents at right
 --             - pad_top    number of lines to pad contents at top
 --             - pad_bottom number of lines to pad contents at bottom
---@return bufnr,winnr buffer and window number of floating window or nil
+--@returns bufnr,winnr buffer and window number of the newly created floating
+---preview window
 function M.open_floating_preview(contents, filetype, opts)
   validate {
     contents = { contents, 't' };
@@ -912,6 +1008,9 @@ do
     severity_floating_highlights[severity] = floating_highlight_name
   end
 
+  --- Clears diagnostics for a buffer.
+  ---
+  --@param bufnr (number) buffer id
   function M.buf_clear_diagnostics(bufnr)
     validate { bufnr = {bufnr, 'n', true} }
     bufnr = bufnr == 0 and api.nvim_get_current_buf() or bufnr
@@ -923,10 +1022,18 @@ do
     api.nvim_buf_clear_namespace(bufnr, diagnostic_ns, 0, -1)
   end
 
+  --- Gets the name of a severity's highlight group.
+  ---
+  --@param severity A member of `vim.lsp.protocol.DiagnosticSeverity`
+  --@returns (string) Highlight group name
   function M.get_severity_highlight_name(severity)
     return severity_highlights[severity]
   end
 
+  --- Gets list of diagnostics for the current line.
+  ---
+  --@returns (table) list of `Diagnostic` tables
+  --@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#diagnostic
   function M.get_line_diagnostics()
     local bufnr = api.nvim_get_current_buf()
     local linenr = api.nvim_win_get_cursor(0)[1] - 1
@@ -941,6 +1048,8 @@ do
     return diagnostics_by_line[linenr] or {}
   end
 
+  --- Displays the diagnostics for the current line in a floating hover
+  --- window.
   function M.show_line_diagnostics()
     -- local marks = api.nvim_buf_get_extmarks(bufnr, diagnostic_ns, {line, 0}, {line, -1}, {})
     -- if #marks == 0 then
@@ -977,10 +1086,10 @@ do
     return popup_bufnr, winnr
   end
 
-  --- Saves the diagnostics (Diagnostic[]) into diagnostics_by_buf
+  --- Saves diagnostics into vim.lsp.util.diagnostics_by_buf[{bufnr}].
   ---
-  --@param bufnr bufnr for which the diagnostics are for.
-  --@param diagnostics Diagnostics[] received from the language server.
+  --@param bufnr (number) buffer id for which the diagnostics are for
+  --@param diagnostics list of `Diagnostic`s received from the LSP server
   function M.buf_diagnostics_save_positions(bufnr, diagnostics)
     validate {
       bufnr = {bufnr, 'n', true};
@@ -1000,6 +1109,10 @@ do
     M.diagnostics_by_buf[bufnr] = diagnostics
   end
 
+  --- Highlights a list of diagnostics in a buffer by underlining them.
+  ---
+  --@param bufnr (number) buffer id
+  --@param diagnostics (list of `Diagnostic`s)
   function M.buf_diagnostics_underline(bufnr, diagnostics)
     for _, diagnostic in ipairs(diagnostics) do
       local start = diagnostic.range["start"]
@@ -1020,11 +1133,18 @@ do
     end
   end
 
+  --- Removes document highlights from a buffer.
+  ---
+  --@param bufnr buffer id
   function M.buf_clear_references(bufnr)
     validate { bufnr = {bufnr, 'n', true} }
     api.nvim_buf_clear_namespace(bufnr, reference_ns, 0, -1)
   end
 
+  --- Shows a list of document highlights for a certain buffer.
+  ---
+  --@param bufnr buffer id
+  --@param references List of `DocumentHighlight` objects to highlight
   function M.buf_highlight_references(bufnr, references)
     validate { bufnr = {bufnr, 'n', true} }
     for _, reference in ipairs(references) do
@@ -1040,11 +1160,19 @@ do
     end
   end
 
+  --- Groups a list of diagnostics by line.
+  ---
+  --@param diagnostics (table) list of `Diagnostic`s
+  --@returns (table) dictionary mapping lines to lists of diagnostics valid on
+  ---those lines
+  --@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#diagnostic
   function M.diagnostics_group_by_line(diagnostics)
     if not diagnostics then return end
     local diagnostics_by_line = {}
     for _, diagnostic in ipairs(diagnostics) do
       local start = diagnostic.range.start
+      -- TODO: Are diagnostics only valid for a single line? I don't understand
+      -- why this would be okay otherwise
       local line_diagnostics = diagnostics_by_line[start.line]
       if not line_diagnostics then
         line_diagnostics = {}
@@ -1055,6 +1183,11 @@ do
     return diagnostics_by_line
   end
 
+  --- Given a list of diagnostics, sets the corresponding virtual text for a
+  --- buffer.
+  ---
+  --@param bufnr buffer id
+  --@param diagnostics (table) list of `Diagnostic`s
   function M.buf_diagnostics_virtual_text(bufnr, diagnostics)
     if not diagnostics then
       return
@@ -1093,8 +1226,7 @@ do
   --- </pre>
   ---
   --@param kind Diagnostic severity kind: See |vim.lsp.protocol.DiagnosticSeverity|
-  ---
-  --@return Count of diagnostics
+  --@returns Count of diagnostics
   function M.buf_diagnostics_count(kind)
     local bufnr = vim.api.nvim_get_current_buf()
     local diagnostics = M.diagnostics_by_buf[bufnr]
@@ -1115,7 +1247,7 @@ do
     [protocol.DiagnosticSeverity.Hint] = "LspDiagnosticsHintSign";
   }
 
-  --- Place signs for each diagnostic in the sign column.
+  --- Places signs for each diagnostic in the sign column.
   ---
   --- Sign characters can be customized with the following commands:
   ---
@@ -1136,8 +1268,11 @@ local position_sort = sort_by_key(function(v)
   return {v.start.line, v.start.character}
 end)
 
--- Returns the items with the byte position calculated correctly and in sorted
--- order.
+--- Returns the items with the byte position calculated correctly and in sorted
+--- order, for display in quickfix and location lists.
+---
+--@param locations (table) list of `Location`s or `LocationLink`s
+--@returns (table) list of items
 function M.locations_to_items(locations)
   local items = {}
   local grouped = setmetatable({}, {
@@ -1180,6 +1315,10 @@ function M.locations_to_items(locations)
   return items
 end
 
+--- Fills current window's location list with given list of items.
+--- Can be obtained with e.g. |vim.lsp.util.locations_to_items()|.
+---
+--@param items (table) list of items
 function M.set_loclist(items)
   vim.fn.setloclist(0, {}, ' ', {
     title = 'Language Server';
@@ -1187,6 +1326,10 @@ function M.set_loclist(items)
   })
 end
 
+--- Fills quickfix list with given list of items.
+--- Can be obtained with e.g. |vim.lsp.util.locations_to_items()|.
+---
+--@param items (table) list of items
 function M.set_qflist(items)
   vim.fn.setqflist({}, ' ', {
     title = 'Language Server';
@@ -1201,10 +1344,11 @@ function M._get_symbol_kind_name(symbol_kind)
   return protocol.SymbolKind[symbol_kind] or "Unknown"
 end
 
---- Convert symbols to quickfix list items
+--- Converts symbols to quickfix list items.
 ---
 --@param symbols DocumentSymbol[] or SymbolInformation[]
 function M.symbols_to_items(symbols, bufnr)
+  --@private
   local function _symbols_to_items(_symbols, _items, _bufnr)
     for _, symbol in ipairs(_symbols) do
       if symbol.location then -- SymbolInformation type
@@ -1239,7 +1383,9 @@ function M.symbols_to_items(symbols, bufnr)
   return _symbols_to_items(symbols, {}, bufnr)
 end
 
--- Remove empty lines from the beginning and end.
+--- Removes empty lines from the beginning and end.
+--@param lines (table) list of lines to trim
+--@returns (table) trimmed list of lines
 function M.trim_empty_lines(lines)
   local start = 1
   for i = 1, #lines do
@@ -1258,11 +1404,13 @@ function M.trim_empty_lines(lines)
   return vim.list_extend({}, lines, start, finish)
 end
 
--- Accepts markdown lines and tries to reduce it to a filetype if it is
--- just a single code block.
--- Note: This modifies the input.
---
--- Returns: filetype or 'markdown' if it was unchanged.
+--- Accepts markdown lines and tries to reduce them to a filetype if they
+--- comprise just a single code block.
+---
+--- CAUTION: Modifies the input in-place!
+---
+--@param lines (table) list of lines
+--@returns (string) filetype or 'markdown' if it was unchanged.
 function M.try_trim_markdown_code_blocks(lines)
   local language_id = lines[1]:match("^```(.*)")
   if language_id then
@@ -1285,6 +1433,7 @@ function M.try_trim_markdown_code_blocks(lines)
 end
 
 local str_utfindex = vim.str_utfindex
+--@private
 local function make_position_param()
   local row, col = unpack(api.nvim_win_get_cursor(0))
   row = row - 1
@@ -1293,6 +1442,10 @@ local function make_position_param()
   return { line = row; character = col; }
 end
 
+--- Creates a `TextDocumentPositionParams` object for the current buffer and cursor position.
+---
+--@returns `TextDocumentPositionParams` object
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocumentPositionParams
 function M.make_position_params()
   return {
     textDocument = M.make_text_document_params();
@@ -1300,6 +1453,13 @@ function M.make_position_params()
   }
 end
 
+--- Using the current position in the current buffer, creates an object that
+--- can be used as a building block for several LSP requests, such as
+--- `textDocument/codeAction`, `textDocument/colorPresentation`,
+--- `textDocument/rangeFormatting`.
+---
+--@returns { textDocument = { uri = `current_file_uri` }, range = { start =
+---`current_position`, end = `current_position` } }
 function M.make_range_params()
   local position = make_position_param()
   return {
@@ -1308,11 +1468,15 @@ function M.make_range_params()
   }
 end
 
+--- Creates a `TextDocumentIdentifier` object for the current buffer.
+---
+--@returns `TextDocumentIdentifier`
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocumentIdentifier
 function M.make_text_document_params()
   return { uri = vim.uri_from_bufnr(0) }
 end
 
---- Get visual width of tabstop.
+--- Returns visual width of tabstop.
 ---
 --@see |softtabstop|
 --@param bufnr (optional, number): Buffer handle, defaults to current
@@ -1324,6 +1488,11 @@ function M.get_effective_tabstop(bufnr)
   return (sts > 0 and sts) or (sts < 0 and bo.shiftwidth) or bo.tabstop
 end
 
+--- Creates a `FormattingOptions` object for the current buffer and cursor position.
+---
+--@param options Table with valid `FormattingOptions` entries
+--@returns `FormattingOptions object
+--@see https://microsoft.github.io/language-server-protocol/specifications/specification-current/#textDocument_formatting
 function M.make_formatting_params(options)
   validate { options = {options, 't', true} }
   options = vim.tbl_extend('keep', options or {}, {
@@ -1336,9 +1505,12 @@ function M.make_formatting_params(options)
   }
 end
 
--- @param buf buffer handle or 0 for current.
--- @param row 0-indexed line
--- @param col 0-indexed byte offset in line
+--- Returns the UTF-32 and UTF-16 offsets for a position in a certain buffer.
+---
+--@param buf buffer id (0 for current)
+--@param row 0-indexed line
+--@param col 0-indexed byte offset in line
+--@returns (number, number) UTF-32 and UTF-16 index of the character in line {row} column {col} in buffer {buf}
 function M.character_offset(buf, row, col)
   local line = api.nvim_buf_get_lines(buf, row, row+1, true)[1]
   -- If the col is past the EOL, use the line length.