{"version":"2.1.221","anchor":"mcp-connection-failure-telemetry-records-negotiation-outcome","canonical_anchor":"mcp-connection-failure-telemetry-records-negotiation-outcome","heading":"MCP connection-failure telemetry records negotiation outcome","tier":"internal","area":"MCP","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221\/e\/mcp-connection-failure-telemetry-records-negotiation-outcome","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221","markdown":"### MCP connection-failure telemetry records negotiation outcome\n\nFailed MCP connections now record how the handshake was negotiated and whether it fell back.\n\n**What**\n\ntengu_mcp_server_connection_failed now describes how the connection was negotiated and whether the modern probe fell back.\n\n**Details**\n\n- Two new field names, both absent from 2.1.220.\n- A fallback records the reason `probe_failed`.\n\n**Evidence**\n\n`probeFellBack`\n\n- Area: MCP\n- Tier: Under the hood\n- Useful: 1\/5\n- Signal: 0\/5"}