fastmcp/docs/python-sdk/fastmcp-fs-decorators.mdx

---
title: decorators
sidebarTitle: decorators
---

# `fastmcp.fs.decorators`


Decorators for marking functions in filesystem-based discovery.

These decorators mark functions with metadata so that FileSystemProvider
can discover and register them. Unlike LocalProvider's decorators, these
do NOT register components immediately - they just store metadata on the
function for later discovery.

Example:
    ```python
    # mcp/tools/greet.py
    from fastmcp.fs import tool

    @tool
    def greet(name: str) -> str:
        '''Greet someone by name.'''
        return f"Hello, {name}!"

    @tool(name="custom-greet", tags={"greeting"})
    def my_greet(name: str) -> str:
        return f"Hi, {name}!"
    ```


## Functions

### `get_fs_meta` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/fs/decorators.py#L86" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
get_fs_meta(fn: Any) -> FSMeta | None
```


Get filesystem metadata from a function if it has been decorated.


### `has_fs_meta` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/fs/decorators.py#L91" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
has_fs_meta(fn: Any) -> bool
```


Check if a function has filesystem metadata.


### `tool` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/fs/decorators.py#L134" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
tool(fn: AnyFunction | str | None = None) -> Any
```


Mark a function as a tool for filesystem-based discovery.

This decorator stores metadata on the function but does NOT register it.
FileSystemProvider discovers marked functions when scanning directories.

Supports multiple calling patterns:
- @tool (without parentheses)
- @tool() (with empty parentheses)
- @tool("custom_name") (with name as first argument)
- @tool(name="custom_name") (with keyword arguments)

**Args:**
- `fn`: The function to decorate, or a name string, or None
- `name`: Optional name for the tool (defaults to function name)
- `title`: Optional title for display
- `description`: Optional description (defaults to docstring)
- `icons`: Optional icons for the tool
- `tags`: Optional tags for categorization
- `output_schema`: Optional JSON schema for output
- `annotations`: Optional tool annotations
- `meta`: Optional metadata dict


### `resource` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/fs/decorators.py#L222" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
resource(uri: str) -> Any
```


Mark a function as a resource for filesystem-based discovery.

This decorator stores metadata on the function but does NOT register it.
FileSystemProvider discovers marked functions when scanning directories.

Unlike @tool and @prompt, @resource REQUIRES a URI argument.

**Args:**
- `uri`: URI for the resource (e.g., "config\://app" or "users\://{user_id}")
- `name`: Optional name for the resource
- `title`: Optional title for display
- `description`: Optional description (defaults to docstring)
- `icons`: Optional icons for the resource
- `mime_type`: Optional MIME type
- `tags`: Optional tags for categorization
- `annotations`: Optional resource annotations
- `meta`: Optional metadata dict


### `prompt` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/fs/decorators.py#L324" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
prompt(fn: AnyFunction | str | None = None) -> Any
```


Mark a function as a prompt for filesystem-based discovery.

This decorator stores metadata on the function but does NOT register it.
FileSystemProvider discovers marked functions when scanning directories.

Supports multiple calling patterns:
- @prompt (without parentheses)
- @prompt() (with empty parentheses)
- @prompt("custom_name") (with name as first argument)
- @prompt(name="custom_name") (with keyword arguments)

**Args:**
- `fn`: The function to decorate, or a name string, or None
- `name`: Optional name for the prompt (defaults to function name)
- `title`: Optional title for display
- `description`: Optional description (defaults to docstring)
- `icons`: Optional icons for the prompt
- `tags`: Optional tags for categorization
- `meta`: Optional metadata dict


## Classes

### `ToolMeta` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/fs/decorators.py#L40" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


Metadata stored on functions decorated with @tool.


### `ResourceMeta` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/fs/decorators.py#L55" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


Metadata stored on functions decorated with @resource.


### `PromptMeta` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/fs/decorators.py#L71" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


Metadata stored on functions decorated with @prompt.