Item 6: tool-surface audit #122

Verdict for item 6 of the 2026-07-13 board build plan: per-tool usage over a ≥3-week post-board window, then merge/trim the MCP tool surface under the pre-registered decision rule (merge recall_episodes into recall if it draws <5% of recall-family calls).

Call counts (recall_metrics, model-facing source='mcp-tool')

Full telemetry window 2026-06-20 → 2026-07-25 (~5 weeks):

• recall_episodes share: 12 / 325 recall+episodes calls = 3.7% (3.6% of all 334 recall-family reads). Sub-window since 2026-07-01: 7 / 259 = 2.7% — usage is falling, not recovering.
• Board (kind='board', push-only serve): 799 serves since 2026-07-13.

Decision

Under the pre-registered 5% threshold → merge. recall_episodes retires as a standalone tool; recall gains mode="overview"|"turns", with "turns" routing to the same engine drill-down path so telemetry keeps kind='episodes' and the historical series stays comparable. Shipped in PR #121.

Secondary findings

• fetch (7 calls): every id-kind envelope shows note expansions only (e:0 in all six post-envelope rows; one older row predates the envelope). The unified n: path from mcp: tool-surface consolidation — remove query_graph/list_projects, hide issue_machine_token, unified fetch (e:/n:), timeline telemetry #58 works in prod and is fetch's dominant real use. (This corrects the 2026-07-24 board-review note that said the calls were all episode ids.)
• Notes had zero quality signal: 87 recall_feedback rows; id prefixes present are e/f/t/w/p — never n:. Root cause: recall never serves n: ids (only the board does), and recall_feedback's description said to report "only ids the recall actually served". PR Merge recall_episodes into recall(mode="turns") + wire n: ids into the feedback loop (item 6) #121 records board/fetch note serves as "n:N" in the served_ids envelopes and rewrites the description to invite board/fetch note ids. No new DDL.
• recall_timeline drew only 2 direct calls, but the timeline leg also serves inside recall() on temporal intent; no action, keep watching.

Scope already shipped before this audit (not redone)

• mcp: tool-surface consolidation — remove query_graph/list_projects, hide issue_machine_token, unified fetch (e:/n:), timeline telemetry #58 (2026-07-13): removed query_graph + list_projects, hid issue_machine_token from listings, unified fetch with e:/n: prefixes.
• mcp: rewrite recall/remember tool descriptions as trigger inventories #47-era (2026-07-12): recall/remember descriptions rewritten as trigger inventories.
• Web bucket deliberately untouched — its overhaul (relevance floors + BM25⊕vector fusion + rerank) shipped separately in feat(recall): self-gating relevance floors for web + timeline buckets #104 on 2026-07-24.