Stateless MCP Breaks Cross-Call Observability Without Session ID

Thirumalaiboobathi · reddit · 2026-08-10

The latest MCP spec removes the Mcp-Session-Id header and initialize handshake, allowing servers to run on serverless architectures. However, this stateless shift breaks cross-call observability.

The maintainer of opentel-mcp shared their troubleshooting experience: in-memory trackers reset per request, breaking retry-loop detection that requires counting across calls. Without a session ID, the system cannot distinguish between three separate clients failing once and a single client failing three times.

To resolve this, v0.10.0 shifts to correlation based on failure fingerprints rather than in-process counting. The author also warns developers relying on the presence of a sessionId field in the transport object for single-connection checks to prepare for potential false positives in future SDK updates.

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