fastmcp.tools.base

Functions

default_serializer ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/tools/base.py#L65" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

default_serializer(data: Any) -> str

Classes

ToolResult ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/tools/base.py#L69" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Methods:

to_mcp_result ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/tools/base.py#L124" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

to_mcp_result(self) -> list[ContentBlock] | tuple[list[ContentBlock], dict[str, Any]] | CallToolResult

Tool ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/tools/base.py#L140" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

Internal tool registration info.

Methods:

to_mcp_tool ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/tools/base.py#L182" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

to_mcp_tool(self, **overrides: Any) -> MCPTool

Convert the FastMCP tool to an MCP tool.

from_function ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/tools/base.py#L218" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

from_function(cls, fn: Callable[..., Any]) -> FunctionTool

Create a Tool from a function.

run ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/tools/base.py#L258" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

run(self, arguments: dict[str, Any]) -> ToolResult

Run the tool with arguments.

This method is not implemented in the base Tool class and must be implemented by subclasses.

run() can EITHER return a list of ContentBlocks, or a tuple of (list of ContentBlocks, dict of structured output).

convert_result ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/tools/base.py#L270" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

convert_result(self, raw_value: Any) -> ToolResult

Convert a raw result to ToolResult.

Handles ToolResult passthrough and converts raw values using the tool's attributes (serializer, output_schema) for proper conversion.

register_with_docket ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/tools/base.py#L379" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

register_with_docket(self, docket: Docket) -> None

Register this tool with docket for background execution.

add_to_docket ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/tools/base.py#L385" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

add_to_docket(self, docket: Docket, arguments: dict[str, Any], **kwargs: Any) -> Execution

Schedule this tool for background execution via docket.

Args:

• docket: The Docket instance
• arguments: Tool arguments
• fn_key: Function lookup key in Docket registry (defaults to self.key)
• task_key: Redis storage key for the result
• **kwargs: Additional kwargs passed to docket.add()

from_tool ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/tools/base.py#L409" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

from_tool(cls, tool: Tool | Callable[..., Any]) -> TransformedTool

get_span_attributes ^{<a href="https://github.com/PrefectHQ/fastmcp/blob/main/src/fastmcp/tools/base.py#L457" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a>}

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