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Documentation Index

Fetch the complete documentation index at: https://gofastmcp.com/llms.txt

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fastmcp.server.middleware.logging

Comprehensive logging middleware for FastMCP servers.

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Functions

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default_serializer 

default_serializer(data: Any) -> str
The default serializer for Payloads in the logging middleware.

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Classes

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BaseLoggingMiddleware

Base class for logging middleware. Methods:

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on_message 

on_message(self, context: MiddlewareContext[Any], call_next: CallNext[Any, Any]) -> Any
Log messages for configured methods.

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LoggingMiddleware

Middleware that provides comprehensive request and response logging. Logs all MCP messages with configurable detail levels. Useful for debugging, monitoring, and understanding server usage patterns.

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StructuredLoggingMiddleware

Middleware that provides structured JSON logging for better log analysis. Outputs structured logs that are easier to parse and analyze with log aggregation tools like ELK stack, Splunk, or cloud logging services.