PR Review Summary

Status: Approved

🪜 Strategic-Fit Decision

Per §9 Strategic-Fit Step-Back:

• Decision: Approve
• Rationale: Free of blocking defects; the implementation matches #13268's Contract Ledger row-for-row. The one cross-skill gap (the new convention is undocumented) is already scoped to the #10757 V4.1 rollout by the ticket's own "later additive refinement" framing — a non-blocking note, not follow-up ceremony on a clean pilot.

Peer-Review Opening: Euclid — clean, disciplined first slice. The Contract Ledger in #13268 is honored row-for-row, the rollout boundary is respected (only file-system opts in), and every named trap is avoided — including the Related: #9953 (not Resolves) close-target discipline. Two non-blocking notes below; merge-eligible.

🧭 Patch-Blind Premise Snapshot

• Inputs Read Before Patch: #13268 (ticket + Contract Ledger Matrix + ACs + Out-of-Scope + Avoided Traps), #9953/#10757 (prior art + parent), current dev ai/mcp/ToolService.mjs (the callTool arg-dispatch + initializeToolMapping listing path), the file-system openapi/toolService, and references/audits/mcp-tool-description-budget.md (the §5.3 home).
• Expected Solution Shape: A bounded tools/list description projection + a lazy get_mcp_tool_handbook tool, gated behind an opt-in config so unmigrated servers are byte-unchanged; detail moved to OpenAPI vendor metadata (NOT hardcoded per-server); structured not-found for unknown ids; per-server unit isolation. Must NOT hardcode the rollout or erase schemas/annotations/names from the listing.
• Patch Verdict: Matches. toolForListing retains name/title/description/inputSchema/outputSchema/annotations (only the description value is compacted); the test asserts readFile.inputSchema.properties.absolutePath.type + healthcheck.annotations.readOnlyHint survive compaction; compactToolDescriptions defaults false (opt-in rollout); getToolHandbook returns {found:false, code:'TOOL_NOT_FOUND'} for unknown ids.

🕸️ Context & Graph Linking

• Target Epic / Issue ID: Resolves #13268
• Related Graph Nodes: Parent #10757 (V4.1 cognitive-load cycle 2); prior art #9953/#9950; convention home references/audits/mcp-tool-description-budget.md.

🔬 Depth Floor

Challenge:

1. Crude mid-word truncation in the no-summary fallback (non-blocking, latent). buildToolListDescription hard-slices at maxLength-3 + ... when a tool has no x-neo-tool-summary/summary. On file-system this never bites (every tool has a short summary), but the next server flipping compactToolDescriptions:true without per-tool x-neo-tool-summary gets mid-word chops. The ledger's fallback row sanctions "derive a bounded value from summary/description," so this matches contract — a word-boundary trim is cheap polish for the rollout.
2. Discoverability of the handbook tool (follow-up). The win depends on agents knowing to call get_mcp_tool_handbook for detail. This slice ships the mechanism; the convention telling agents so isn't documented yet (see Cross-Skill). Deliberately deferred by the ticket.

Rhetorical-Drift Audit: Pass. "opt-in compact projection", "lazy-loaded getToolHandbook()", "unmigrated servers keep their current list-description behavior" map 1:1 to the code; the unmigrated servers keep their existing list description behavior test substantiates the last claim. Evidence: L2 → L2 required. No residuals. is accurate. Provenance: internal origin declared (V4.1, session 4ed21ddf…); no external-framework port.

🧠 Graph Ingestion Notes

• [RETROSPECTIVE]: Progressive disclosure (Map vs Atlas) applied to the MCP tool surface — compact tools/list (always-loaded Map) + lazy get_mcp_tool_handbook (on-demand Atlas). The proactive seam for the context-tax problem §5.3 flags reactively. The opt-in-default + ledger-exact rollout discipline is the model for landing a cross-cutting pattern without a big-bang migration.
• [KB_GAP]: The x-neo-tool-summary / x-neo-tool-handbook vendor-extension convention is now live but unindexed — ask_knowledge_base has no document describing when/how to use it. Folds into the Cross-Skill follow-up.

🎯 Close-Target Audit

• Close-targets: Resolves #13268 (only magic-close keyword). Related: #10757, Related: #9953 are non-closing extras.
• #13268 labels: enhancement, developer-experience, ai, architecture, model-experience — not epic-labeled. Valid leaf. ✅
• Verified Related: #9953 (NOT Resolves #9953) — honors the ticket's "do not auto-close the broad prior-art ticket" trap. ✅

Findings: Pass.

📑 Contract Completeness Audit

#13268 carries a full Contract Ledger Matrix (4 rows). Audited the diff against each:

• tools/list projection — bounded descriptions preserving name/title/inputSchema/outputSchema/annotations → ✅ (test asserts schema + annotation survival).
• get_mcp_tool_handbook (new) — one-tool detail, structured not-found, normal dispatch → ✅ (getToolHandbook + serviceMapping wiring; valid + missing-id tested).
• Handbook content source — preserved in lazy body, fallback marks derived → ✅ (source field names origin: x-neo-tool-handbook/description/summary).
• Rollout boundary — one server opts in, unmigrated unchanged → ✅ (default false; unmigrated-behavior test).

Findings: Pass — implementation matches the ledger exactly, no drift.

🪜 Evidence Audit

Findings: N/A — close-target ACs are fully covered by unit tests (pure handbook function + compaction projection; no runtime/visual/restart/wake AC). PR declares Evidence: L2 → L2 required. No residuals., which is accurate.

📡 MCP-Tool-Description Budget Audit

ai/mcp/server/file-system/openapi.yaml touched. Audited the added/modified descriptions:

• /tool/handbook endpoint description: "Returns lazy-loaded usage detail for one file-system MCP tool." — single-line, call-site usage, ~60 chars. ✅
• read_file x-neo-tool-summary: "Read a workspace file by absolute path." — single-line, ≤ the 120 budget. ✅
• read_file x-neo-tool-handbook: multi-line block-literal — but vendor metadata that does NOT load into tools/list (lazy-fetched via getToolHandbook). It is the §5.3 remediation, not a violation: it MOVES detail off the always-loaded surface. No ticket refs / phase sequencing / session IDs in any description. 1024-char cap comfortably respected.

Findings: Pass — this PR is the architectural answer to §5.3, not a budget regression.

🔗 Cross-Skill Integration Audit

The PR introduces a new MCP tool surface (get_mcp_tool_handbook) AND a reusable convention (x-neo-tool-summary / x-neo-tool-handbook vendor extensions + compactToolDescriptions opt-in). §8.1 fires.

• V-B-A'd: grepped .agents + learn (md) for the convention tokens → zero hits. The convention is documented nowhere on dev. The natural home — references/audits/mcp-tool-description-budget.md (the §5.3 audit) — is unaware of the handbook remediation: a reviewer running §5.3 today would say "shorten the description," not "move detail to x-neo-tool-handbook."

Findings (non-blocking): The ticket deliberately scoped repo-wide convention work as a "later additive refinement" (Out-of-Scope: repo-wide truncation), so this is correctly NOT a gap this PR must close. As the pattern reaches a 2nd server (rollout-boundary row + #10757), add a one-line pointer in references/audits/mcp-tool-description-budget.md so §5.3 routes description-bloat findings to the handbook remediation. Already scoped under #10757 — no new ticket needed.

🧪 Test-Execution & Location Audit

• Location: test/playwright/unit/ai/mcp/server/McpServerListToolsSmoke.spec.mjs — canonical MCP test dir. ✅
• Execution: Checked out the PR's 4 files into a clean dev workspace and ran the spec → 21 passed — including file-system exposes compact list descriptions plus lazy-loaded handbook detail (#13268) and unmigrated servers keep their existing list description behavior (#13268).
• CI: all 9 checks SUCCESS (lint-pr-body, lint, check, Classify test scope, integration-unified, unit, CodeQL, Analyze javascript).

Findings: Tests pass; canonical placement; CI green.

📋 Required Actions

No required actions — eligible for human merge.

(Two non-blocking notes for the rollout, not this PR: word-boundary truncation in the no-summary fallback; document the x-neo-tool-* convention in the §5.3 audit doc as a 2nd server adopts it.)

📊 Evaluation Metrics

• [ARCH_ALIGNMENT]: 95 — config-driven opt-in projection, progressive-disclosure primitive, DRY resolveEffectiveToolName extraction, backward-compatible default. 5 deducted: the no-summary fallback hard-slices mid-word rather than at a word boundary — sanctioned by the ledger but a crude edge for future adopters.
• [CONTENT_COMPLETENESS]: 92 — every new method/config carries @summary + param/return JSDoc; Fat-Ticket body with Evidence/Deltas/Test-Evidence anchors; Contract Ledger honored. 8 deducted: the new vendor-extension convention ships undocumented ([KB_GAP]) — deliberately deferred, but a real present gap.
• [EXECUTION_QUALITY]: 92 — tests green locally (21/21) + CI green; arg-dispatch V-B-A-confirmed (argNames positional map passes the toolId string, not the object); structured not-found; ledger-exact. 8 deducted: the crude mid-word truncation is latent execution-polish debt.
• [PRODUCTIVITY]: 100 — all 7 ACs map to shipped code+tests: shared seam ✅, one-server get_mcp_tool_handbook ✅, bounded descriptions preserving schemas ✅, structured not-found ✅, unmigrated compatibility ✅, focused tests (4 cases) ✅, Related #9953 non-close ✅. Considered missed / partial / deferred ACs — none apply.
• [IMPACT]: 80 — establishes the MCP tool-handbook progressive-disclosure primitive; as it rolls out it cuts every consuming agent's per-turn context tax. Subsystem-level seed.
• [COMPLEXITY]: 55 — Moderate: opt-in projection config + 4 helper methods + openapi vendor-extension convention + lazy-cache + DRY refactor across two call-sites; the description-source cascade and argNames positional dispatch must be internalized before extending.
• [EFFORT_PROFILE]: Quick Win — high ROI (seeds a context-tax-reduction pattern) at well-scoped, fully-tested, low-moderate complexity.

Solid slice, Euclid — approving. The ledger-driven discipline (implementation matches all 4 rows + every avoided-trap honored) is exactly the shape that makes a cross-cutting pattern safe to roll out incrementally. The [RETROSPECTIVE] above captures the Map/Atlas-for-tools takeaway for the graph.