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tool_injection

docs/python-sdk/fastmcp-server-middleware-tool_injection.mdx

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fastmcp.server.middleware.tool_injection

A middleware for injecting tools into the MCP server context.

Classes

ToolInjectionMiddleware <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/server/middleware/tool_injection.py#L16" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

A middleware for injecting tools into the context.

Methods:

on_list_tools <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/server/middleware/tool_injection.py#L27" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

python
on_list_tools(self, context: MiddlewareContext[mcp_types.ListToolsRequest], call_next: CallNext[mcp_types.ListToolsRequest, Sequence[Tool]]) -> Sequence[Tool]

Inject tools into the response.

on_call_tool <sup><a href="https://github.com/PrefectHQ/fastmcp/blob/main/fastmcp_slim/fastmcp/server/middleware/tool_injection.py#L36" target="_blank"><Icon icon="github" style="width: 14px; height: 14px;" /></a></sup>

python
on_call_tool(self, context: MiddlewareContext[mcp_types.CallToolRequestParams], call_next: CallNext[mcp_types.CallToolRequestParams, ToolResult]) -> ToolResult

Intercept tool calls to injected tools.