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Documentation Index

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fastmcp.utilities.components

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Functions

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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.

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Classes

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FastMCPMeta

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FastMCPComponent

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

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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”

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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.

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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.

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enable 

enable(self) -> None
Removed in 3.0. Use server.enable(keys=[…]) instead.

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disable 

disable(self) -> None
Removed in 3.0. Use server.disable(keys=[…]) instead.

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copy 

copy(self) -> Self
Create a copy of the component.

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register_with_docket 

register_with_docket(self, docket: Docket) -> None
Register this component with docket for background execution. No-ops if task_config.mode is “forbidden”. Subclasses override to register their callable (self.run, self.read, self.render, or self.fn).

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add_to_docket 

add_to_docket(self, docket: Docket, *args: Any, **kwargs: Any) -> Execution
Schedule this component for background execution via docket. Subclasses override this to handle their specific calling conventions:
  • Tool: add_to_docket(docket, arguments: dict, **kwargs)
  • Resource: add_to_docket(docket, **kwargs)
  • ResourceTemplate: add_to_docket(docket, params: dict, **kwargs)
  • Prompt: add_to_docket(docket, arguments: dict | None, **kwargs)
The **kwargs are passed through to docket.add() (e.g., key=task_key).

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get_span_attributes 

get_span_attributes(self) -> dict[str, Any]
Return span attributes for telemetry. Subclasses should call super() and merge their specific attributes.