`fastmcp.utilities.components`

Functions

`get_fastmcp_metadata`

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.

`public_result_meta`

public_result_meta(meta: dict[str, Any] | None) -> dict[str, Any] | None

Strip FastMCP’s internal bookkeeping out of component meta. Component meta carries private entries under the fastmcp namespace (e.g. _internal.visibility) that must never reach the wire. Listings already filter these via FastMCPComponent.get_meta(); results that carry component meta (resource contents, prompt results) need the same treatment. Returns None when nothing public remains, so components without user metadata keep an absent _meta rather than an empty object.

Classes

`FastMCPMeta`

`FastMCPComponent`

Base class for FastMCP tools, prompts, resources, and resource templates. Methods:

`make_key`

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`

key(self) -> str

The globally unique lookup key for this component. Format: ”:@” or ”:@” 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`

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`

enable(self) -> None

Removed in 3.0. Use server.enable(keys=[…]) instead.

`disable`

disable(self) -> None

Removed in 3.0. Use server.disable(keys=[…]) instead.

`copy`

copy(self) -> Self

Create a copy of the component.

`get_span_attributes`

get_span_attributes(self) -> dict[str, Any]

Return span attributes for telemetry. Subclasses should call super() and merge their specific attributes.

fastmcp.apps

fastmcp.cli

fastmcp.client

fastmcp.experimental

fastmcp.prompts

fastmcp.resources

fastmcp.server

fastmcp.tools