fastmcp.server.auth.middleware

Enhanced authentication middleware with better error messages.

This module provides enhanced versions of MCP SDK authentication middleware that return more helpful error messages for developers troubleshooting authentication issues.

Implements RFC 6750 §3.1 compliance by distinguishing between missing authentication (no error attribute) and invalid authentication (with error).

Classes

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

Enhanced authentication middleware with detailed error messages.

Extends the SDK's RequireAuthMiddleware to provide more actionable error messages when authentication fails. This helps developers understand what went wrong and how to fix it.

Also implements RFC 6750 §3.1 compliance by distinguishing between missing authentication (initial discovery) and invalid authentication (token validation failure).