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fastmcp.server.providers.local_provider.decorators.tools

Tool decorator mixin for LocalProvider. This module provides the ToolDecoratorMixin class that adds tool registration functionality to LocalProvider.

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Classes

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ToolDecoratorMixin

Mixin class providing tool decorator functionality for LocalProvider. This mixin contains all methods related to:
  • Tool registration via add_tool()
  • Tool decorator (@provider.tool)
Methods:

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add_tool 

add_tool(self: LocalProvider, tool: Tool | Callable[..., Any]) -> Tool
Add a tool to this provider’s storage. Accepts either a Tool object or a decorated function with fastmcp metadata.

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tool 

tool(self: LocalProvider, name_or_fn: AnyFunction) -> FunctionTool

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tool 

tool(self: LocalProvider, name_or_fn: str | None = None) -> Callable[[AnyFunction], FunctionTool]

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tool 

tool(self: LocalProvider, name_or_fn: str | AnyFunction | None = None) -> Callable[[AnyFunction], FunctionTool] | FunctionTool | partial[Callable[[AnyFunction], FunctionTool] | FunctionTool]
Decorator to register a tool. This decorator supports multiple calling patterns:
  • @provider.tool (without parentheses)
  • @provider.tool() (with empty parentheses)
  • @provider.tool(“custom_name”) (with name as first argument)
  • @provider.tool(name=“custom_name”) (with name as keyword argument)
  • provider.tool(function, name=“custom_name”) (direct function call)
Args:
  • name_or_fn: Either a function (when used as @tool), a string name, or None
  • name: Optional name for the tool (keyword-only, alternative to name_or_fn)
  • title: Optional title for the tool
  • description: Optional description of what the tool does
  • icons: Optional icons for the tool
  • tags: Optional set of tags for categorizing the tool
  • output_schema: Optional JSON schema for the tool’s output
  • annotations: Optional annotations about the tool’s behavior
  • exclude_args: Optional list of argument names to exclude from the tool schema
  • meta: Optional meta information about the tool
  • enabled: Whether the tool is enabled (default True). If False, adds to blocklist.
  • task: Optional task configuration for background execution
  • serializer: Deprecated. Return ToolResult from your tools for full control over serialization.
Returns:
  • The registered FunctionTool or a decorator function.