diff --git a/lua/avante/llm_tools.lua b/lua/avante/llm_tools.lua
index 0ae1323..d4988a9 100644
--- a/lua/avante/llm_tools.lua
+++ b/lua/avante/llm_tools.lua
@@ -34,9 +34,7 @@ local function has_permission_to_access(abs_path)
 end
 
 ---@param opts { rel_path: string, max_depth?: integer }
----@param on_log? fun(log: string): nil
----@return string files
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.list_files(opts, on_log)
   local abs_path = get_abs_path(opts.rel_path)
   if not has_permission_to_access(abs_path) then return "", "No permission to access path: " .. abs_path end
@@ -56,9 +54,7 @@ function M.list_files(opts, on_log)
 end
 
 ---@param opts { rel_path: string, keyword: string }
----@param on_log? fun(log: string): nil
----@return string files
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.search_files(opts, on_log)
   local abs_path = get_abs_path(opts.rel_path)
   if not has_permission_to_access(abs_path) then return "", "No permission to access path: " .. abs_path end
@@ -75,9 +71,7 @@ function M.search_files(opts, on_log)
 end
 
 ---@param opts { rel_path: string, keyword: string }
----@param on_log? fun(log: string): nil
----@return string result
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.search(opts, on_log)
   local abs_path = get_abs_path(opts.rel_path)
   if not has_permission_to_access(abs_path) then return "", "No permission to access path: " .. abs_path end
@@ -114,9 +108,7 @@ function M.search(opts, on_log)
 end
 
 ---@param opts { rel_path: string }
----@param on_log? fun(log: string): nil
----@return string definitions
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.read_file_toplevel_symbols(opts, on_log)
   local RepoMap = require("avante.repo_map")
   local abs_path = get_abs_path(opts.rel_path)
@@ -133,9 +125,7 @@ function M.read_file_toplevel_symbols(opts, on_log)
 end
 
 ---@param opts { rel_path: string }
----@param on_log? fun(log: string): nil
----@return string content
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.read_file(opts, on_log)
   local abs_path = get_abs_path(opts.rel_path)
   if not has_permission_to_access(abs_path) then return "", "No permission to access path: " .. abs_path end
@@ -148,9 +138,7 @@ function M.read_file(opts, on_log)
 end
 
 ---@param opts { rel_path: string }
----@param on_log? fun(log: string): nil
----@return boolean success
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.create_file(opts, on_log)
   local abs_path = get_abs_path(opts.rel_path)
   if not has_permission_to_access(abs_path) then return false, "No permission to access path: " .. abs_path end
@@ -169,9 +157,7 @@ function M.create_file(opts, on_log)
 end
 
 ---@param opts { rel_path: string, new_rel_path: string }
----@param on_log? fun(log: string): nil
----@return boolean success
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.rename_file(opts, on_log)
   local abs_path = get_abs_path(opts.rel_path)
   if not has_permission_to_access(abs_path) then return false, "No permission to access path: " .. abs_path end
@@ -189,9 +175,7 @@ function M.rename_file(opts, on_log)
 end
 
 ---@param opts { rel_path: string, new_rel_path: string }
----@param on_log? fun(log: string): nil
----@return boolean success
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.copy_file(opts, on_log)
   local abs_path = get_abs_path(opts.rel_path)
   if not has_permission_to_access(abs_path) then return false, "No permission to access path: " .. abs_path end
@@ -206,9 +190,7 @@ function M.copy_file(opts, on_log)
 end
 
 ---@param opts { rel_path: string }
----@param on_log? fun(log: string): nil
----@return boolean success
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.delete_file(opts, on_log)
   local abs_path = get_abs_path(opts.rel_path)
   if not has_permission_to_access(abs_path) then return false, "No permission to access path: " .. abs_path end
@@ -221,9 +203,7 @@ function M.delete_file(opts, on_log)
 end
 
 ---@param opts { rel_path: string }
----@param on_log? fun(log: string): nil
----@return boolean success
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.create_dir(opts, on_log)
   local abs_path = get_abs_path(opts.rel_path)
   if not has_permission_to_access(abs_path) then return false, "No permission to access path: " .. abs_path end
@@ -237,9 +217,7 @@ function M.create_dir(opts, on_log)
 end
 
 ---@param opts { rel_path: string, new_rel_path: string }
----@param on_log? fun(log: string): nil
----@return boolean success
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.rename_dir(opts, on_log)
   local abs_path = get_abs_path(opts.rel_path)
   if not has_permission_to_access(abs_path) then return false, "No permission to access path: " .. abs_path end
@@ -257,9 +235,7 @@ function M.rename_dir(opts, on_log)
 end
 
 ---@param opts { rel_path: string }
----@param on_log? fun(log: string): nil
----@return boolean success
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.delete_dir(opts, on_log)
   local abs_path = get_abs_path(opts.rel_path)
   if not has_permission_to_access(abs_path) then return false, "No permission to access path: " .. abs_path end
@@ -274,9 +250,7 @@ function M.delete_dir(opts, on_log)
 end
 
 ---@param opts { rel_path: string, command: string }
----@param on_log? fun(log: string): nil
----@return string|boolean result
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.run_command(opts, on_log)
   local abs_path = get_abs_path(opts.rel_path)
   if not has_permission_to_access(abs_path) then return false, "No permission to access path: " .. abs_path end
@@ -300,9 +274,7 @@ function M.run_command(opts, on_log)
 end
 
 ---@param opts { query: string }
----@param on_log? fun(log: string): nil
----@return string|nil result
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.web_search(opts, on_log)
   local provider_type = Config.web_search_engine.provider
   if provider_type == nil then return nil, "Search engine provider is not set" end
@@ -405,9 +377,7 @@ function M.web_search(opts, on_log)
 end
 
 ---@param opts { url: string }
----@param on_log? fun(log: string): nil
----@return string|nil result
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.fetch(opts, on_log)
   if on_log then on_log("url: " .. opts.url) end
   local Html2Md = require("avante.html2md")
@@ -417,9 +387,7 @@ function M.fetch(opts, on_log)
 end
 
 ---@param opts { scope?: string }
----@param on_log? fun(log: string): nil
----@return string|nil result
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.git_diff(opts, on_log)
   local git_cmd = vim.fn.exepath("git")
   if git_cmd == "" then return nil, "Git command not found" end
@@ -449,9 +417,7 @@ function M.git_diff(opts, on_log)
 end
 
 ---@param opts { message: string, scope?: string }
----@param on_log? fun(log: string): nil
----@return boolean success
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.git_commit(opts, on_log)
   local git_cmd = vim.fn.exepath("git")
   if git_cmd == "" then return false, "Git command not found" end
@@ -539,9 +505,7 @@ function M.git_commit(opts, on_log)
 end
 
 ---@param opts { query: string }
----@param on_log? fun(log: string): nil
----@return string|nil result
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.rag_search(opts, on_log)
   if not Config.rag_service.enabled then return nil, "Rag service is not enabled" end
   if not opts.query then return nil, "No query provided" end
@@ -555,9 +519,7 @@ function M.rag_search(opts, on_log)
 end
 
 ---@param opts { code: string, rel_path: string, container_image?: string }
----@param on_log? fun(log: string): nil
----@return string|nil result
----@return string|nil error
+---@type AvanteLLMToolFunc
 function M.python(opts, on_log)
   local abs_path = get_abs_path(opts.rel_path)
   if not has_permission_to_access(abs_path) then return nil, "No permission to access path: " .. abs_path end
@@ -1147,22 +1109,28 @@ M._tools = {
 ---@return string | nil error
 function M.process_tool_use(tools, tool_use, on_log)
   Utils.debug("use tool", tool_use.name, tool_use.input_json)
-  local tool = vim.iter(tools):find(function(tool) return tool.name == tool_use.name end)
+  ---@type AvanteLLMTool?
+  local tool = vim.iter(tools):find(function(tool) return tool.name == tool_use.name end) ---@param tool AvanteLLMTool
   if tool == nil then return end
   local input_json = vim.json.decode(tool_use.input_json)
   local func = tool.func or M[tool.name]
-  if on_log then on_log(tool_use.name, "running tool") end
+  if on_log then on_log(tool.name, "running tool") end
   local result, error = func(input_json, function(log)
-    if on_log then on_log(tool_use.name, log) end
+    if on_log then on_log(tool.name, log) end
   end)
-  if on_log then on_log(tool_use.name, "tool finished") end
+  if on_log then on_log(tool.name, "tool finished") end
   -- Utils.debug("result", result)
   -- Utils.debug("error", error)
   if error ~= nil then
-    if on_log then on_log(tool_use.name, "Error: " .. error) end
+    if on_log then on_log(tool.name, "Error: " .. error) end
   end
-  if result ~= nil and type(result) ~= "string" then result = vim.json.encode(result) end
-  return result, error
+  local result_str ---@type string?
+  if type(result) == "string" then
+    result_str = result
+  elseif result ~= nil then
+    result_str = vim.json.encode(result)
+  end
+  return result_str, error
 end
 
 ---@param tool_use AvanteLLMToolUse
diff --git a/lua/avante/sidebar.lua b/lua/avante/sidebar.lua
index 9696ac5..2001483 100644
--- a/lua/avante/sidebar.lua
+++ b/lua/avante/sidebar.lua
@@ -2292,8 +2292,7 @@ function Sidebar:create_input_container(opts)
     name = "add_file_to_context",
     description = "Add a file to the context",
     ---@param input { rel_path: string }
-    ---@return string | nil result
-    ---@return string | nil error
+    ---@type AvanteLLMToolFunc
     func = function(input)
       self.file_selector:add_selected_file(input.rel_path)
       return "Added file to context", nil
@@ -2309,8 +2308,7 @@ function Sidebar:create_input_container(opts)
     name = "remove_file_from_context",
     description = "Remove a file from the context",
     ---@param input { rel_path: string }
-    ---@return string | nil result
-    ---@return string | nil error
+    ---@type AvanteLLMToolFunc
     func = function(input)
       self.file_selector:remove_selected_file(input.rel_path)
       return "Removed file from context", nil
diff --git a/lua/avante/types.lua b/lua/avante/types.lua
index 9034e63..79ae650 100644
--- a/lua/avante/types.lua
+++ b/lua/avante/types.lua
@@ -323,10 +323,12 @@ vim.g.avante_login = vim.g.avante_login
 ---@field on_stop AvanteLLMStopCallback
 ---@field on_tool_log? function(tool_name: string, log: string): nil
 ---
+---@alias AvanteLLMToolFunc fun(input: any, on_log?: (fun(log: string): nil) | nil): (boolean | string | nil, string | nil)
+---
 ---@class AvanteLLMTool
 ---@field name string
 ---@field description string
----@field func? fun(input: any): (string | nil, string | nil)
+---@field func? AvanteLLMToolFunc
 ---@field param AvanteLLMToolParam
 ---@field returns AvanteLLMToolReturn[]
 ---@field enabled? fun(): boolean