FastMCP OpenTelemetry Middleware

Example Use Cases

• 1

  Propagate OpenTelemetry tracing context through MCP _meta fields.

• 2

  Automatically create server spans for FastMCP tool invocations.

• 3

  Enriched trace data with tool names, call IDs, and optional arguments.

Description

This middleware enables FastMCP servers to extract OpenTelemetry context from MCP _meta fields and automatically create server spans for tool invocations. It enriches traces with tool names, call IDs, namespaces, and optionally tool arguments, improving observability and traceability. The package supports compatibility with multiple FastMCP versions and offers customization options including Langfuse-compatible metadata. It simplifies distributed tracing for FastMCP applications by leveraging the Model Context Protocol's propagation standards.