fastmcp/docs/python-sdk/fastmcp-utilities-components.mdx
2026-07-23 20:52:17 -04:00

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---
title: components
sidebarTitle: components
---
# `fastmcp.utilities.components`
## Functions
### `get_fastmcp_metadata` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/utilities/components.py#L22" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
```python
get_fastmcp_metadata(meta: dict[str, Any] | None) -> FastMCPMeta
```
Extract FastMCP metadata from a component's meta dict.
Handles both the current `fastmcp` namespace and the legacy `_fastmcp`
namespace for compatibility with older FastMCP servers.
## Classes
### `FastMCPMeta` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/utilities/components.py#L16" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
### `FastMCPComponent` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/utilities/components.py#L70" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
Base class for FastMCP tools, prompts, resources, and resource templates.
**Methods:**
#### `make_key` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/utilities/components.py#L125" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
```python
make_key(cls, identifier: str) -> str
```
Construct the lookup key for this component type.
**Args:**
- `identifier`: The raw identifier (name for tools/prompts, uri for resources)
**Returns:**
- A prefixed key like "tool:name" or "resource:uri"
#### `key` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/utilities/components.py#L139" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
```python
key(self) -> str
```
The globally unique lookup key for this component.
Format: "{key_prefix}:{identifier}@{version}" or "{key_prefix}:{identifier}@"
e.g. "tool:my_tool@v2", "tool:my_tool@", "resource:file://x.txt@"
The @ suffix is ALWAYS present to enable unambiguous parsing of keys
(URIs may contain @ characters, so we always include the delimiter).
Subclasses should override this to use their specific identifier.
Base implementation uses name.
Prefer `.key` over ad-hoc `name or uri or uri_template` logic for any
cross-component identity work (dedupe, grouping, collision detection,
lookup tables). It encodes type, identifier, and version, so variants
of the same component don't falsely collide with each other, and
cross-type identifiers (e.g. a tool and a resource both named "foo")
can't clash.
#### `get_meta` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/utilities/components.py#L161" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
```python
get_meta(self) -> dict[str, Any]
```
Get the meta information about the component.
Returns a dict that always includes a `fastmcp` key containing:
- `tags`: sorted list of component tags
- `version`: component version (only if set)
Internal keys (prefixed with `_`) are stripped from the fastmcp namespace.
#### `enable` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/utilities/components.py#L209" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
```python
enable(self) -> None
```
Removed in 3.0. Use server.enable(keys=[...]) instead.
#### `disable` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/utilities/components.py#L216" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
```python
disable(self) -> None
```
Removed in 3.0. Use server.disable(keys=[...]) instead.
#### `copy` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/utilities/components.py#L223" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
```python
copy(self) -> Self
```
Create a copy of the component.
#### `get_span_attributes` <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/utilities/components.py#L227" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>
```python
get_span_attributes(self) -> dict[str, Any]
```
Return span attributes for telemetry.
Subclasses should call super() and merge their specific attributes.