---
title: function_resource
sidebarTitle: function_resource
---

# `fastmcp.resources.function_resource`


Standalone @resource decorator for FastMCP.

## Functions

### `resource` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/resources/function_resource.py#L236" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
resource(uri: str) -> Callable[[F], F]
```


Standalone decorator to mark a function as an MCP resource.

Returns the original function with metadata attached. Register with a server
using mcp.add_resource().


## Classes

### `DecoratedResource` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/resources/function_resource.py#L36" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


Protocol for functions decorated with @resource.


### `ResourceMeta` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/resources/function_resource.py#L45" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


Metadata attached to functions by the @resource decorator.


### `FunctionResource` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/resources/function_resource.py#L64" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>


A resource that defers data loading by wrapping a function.

The function is only called when the resource is read, allowing for lazy loading
of potentially expensive data. This is particularly useful when listing resources,
as the function won't be called until the resource is actually accessed.

The function can return:
- str for text content (default)
- bytes for binary content
- other types will be converted to JSON


**Methods:**

#### `from_function` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/resources/function_resource.py#L80" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
from_function(cls, fn: Callable[..., Any], uri: str | AnyUrl | None = None) -> FunctionResource
```

Create a FunctionResource from a function.

**Args:**
- `fn`: The function to wrap
- `uri`: The URI for the resource (required if metadata not provided)
- `metadata`: ResourceMeta object with all configuration. If provided,
individual parameters must not be passed.
- `name, title, etc.`: Individual parameters for backwards compatibility.
Cannot be used together with metadata parameter.


#### `read` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/resources/function_resource.py#L204" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
read(self) -> str | bytes | ResourceResult
```

Read the resource by calling the wrapped function.


#### `register_with_docket` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/resources/function_resource.py#L225" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

```python
register_with_docket(self, docket: Docket) -> None
```

Register this resource with docket for background execution.

FunctionResource registers the underlying function, which has the user's
Depends parameters for docket to resolve.

