{"version":"2.1.221","anchor":"discovery-cache-misses-are-classified-in-telemetry","canonical_anchor":"discovery-cache-misses-are-classified-in-telemetry","heading":"Discovery-cache misses are classified in telemetry","tier":"internal","area":"MCP","scope":null,"heads_up":null,"url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221\/e\/discovery-cache-misses-are-classified-in-telemetry","release_url":"https:\/\/changelogs.core-directive.com\/v\/2.1.221","markdown":"### Discovery-cache misses are classified in telemetry\n\nMCP tool discovery now logs whether the cache was used, and servers with skills or channels deliberately skip it.\n\n**What**\n\nA new event records where a server's tools came from, distinguishing real cache misses from deliberate bypasses.\n\n**Details**\n\n- `tengu_mcp_discovery_source` reports `cache_fresh` or `cache_stale` for hits, and a normalized reason otherwise.\n- Reasons meaning \"we connected anyway\" collapse to `live`.\n- Genuine misses report `miss_disabled`, `miss_expired`, `miss_corrupt`, `miss_strike` or `miss_no_fingerprint`.\n- Two mapped reasons are new opt-outs: `skills-capable` and `channel-capable` servers deliberately bypass the cache.\n- Gated on `tengu_mcp_discovery_cache`, which falls back to enabled.\n\n**Evidence**\n\n`miss_no_fingerprint`\n\n- Flag `tengu_mcp_discovery_cache`: Not enough to say (read for one account on one subscription tier against v2.1.221; this account: no value returned, anonymous baseline: no value returned, compiled default: on) These values were read against a different version of Claude Code, so treat them as the nearest reading available instead of one taken on this release.\n- Area: MCP\n- Tier: Under the hood\n- Useful: 2\/5\n- Signal: 0\/5"}