{"version":"2.1.221","anchor":"connection-telemetry-gains-negotiation-and-protocol-fields","canonical_anchor":"connection-telemetry-gains-negotiation-and-protocol-fields","heading":"Connection telemetry gains negotiation and protocol fields","tier":"internal","area":"MCP","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221\/e\/connection-telemetry-gains-negotiation-and-protocol-fields","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221","markdown":"### Connection telemetry gains negotiation and protocol fields\n\nMCP debug output now shows which protocol version and path a server connection used.\n\n**What**\n\nMCP connection events now report which protocol path was taken.\n\n**Details**\n\n- `tengu_mcp_server_connection_succeeded` adds `negotiationMode`, `protocolEra`, `negotiatedProtocolVersion` and `probeFellBack`.\n- `tengu_mcp_server_connection_failed` adds `negotiationMode` and `probeFellBack`.\n- The negotiated version is passed through an allowlist of known revisions and reported as `other` if it is not one of them.\n- The debug line for a successful connect now prints protocolEra and negotiatedProtocolVersion alongside the capability summary.\n\n**Evidence**\n\n`negotiatedProtocolVersion`\n\n- Area: MCP\n- Tier: Under the hood\n- Useful: 2\/5\n- Signal: 0\/5"}