Conciseness

The body is dense and rule-driven ('Hard limit: 16 MB per document', 'Order compound index keys by ESR') with no concept tutorials, but the 12-line 'Keeping this skill current' maintenance section and the forward-reference line 'MongoDB ships a major release roughly yearly. See [Keeping this skill current]…' are maintenance-time rather than answer-time content — minor over-explanation that could be trimmed, so anchor 4 rather than the every-token-earns-its-place anchor 5.

Actionability

Concrete, specific guidance throughout: the executable diagnostic heuristic 'nReturned ≈ totalKeysExamined ≈ totalDocsExamined', the copy-pasteable command 'grep -rn "(≥" ~/.claude/skills/mongodb-expert/', and precise defaults ('default chunk size 128 MB since 5.2', 'w:"majority" is the 8.0 default (≥5.0)'). Most rules are assertions whose executable detail is deferred to the reference files, matching anchor 4's 'minor gaps' rather than anchor 5's fully copy-paste-ready coverage.

Workflow Clarity

The routing table ('Which reference to load') gives an unambiguous task/symptom → file decision procedure, and the maintenance procedure is a numbered 5-step sequence with checking built into steps 2–4. Validation checkpoints are otherwise implicit (e.g., 'aim for explain("executionStats")' is a check described, not an enforced step), so anchor 4's 'most checkpoints present; minor validation gaps' fits better than anchor 5.

Progressive Disclosure

A clear overview with four one-level-deep references (references/schema-design.md, performance.md, benchmarking.md, standard-practices.md — all verified to exist), each mapped from concrete task/symptom rows in a routing table, with quick rules inline and detail appropriately split out. This matches the anchor-5 example structure of well-signaled one-level-deep references with easy navigation.

Specificity

Lists multiple specific concrete actions across four capability areas — 'designing a schema or collection (embed vs reference, data modeling, BSON types, schema validation)', 'optimizing performance (indexes, ESR rule, explain() / slow query tuning, aggregation pipelines, covered queries)', 'benchmarking or monitoring (profiler, mongostat, working set, executionStats)' — with no coverage gaps, matching the comprehensive anchor rather than the 'minor gaps' anchor 4.

Completeness

Explicitly answers 'when' with 'Use when working with MongoDB —' followed by four concrete trigger scenarios, and 'what' via the enumerated actions and 'Covers MongoDB 8.0 with version-gated notes back to 4.x'. Both are explicit with concrete trigger phrases, matching the anchor-5 example structure; it does not fall to anchor 4 since the 'when' is highly specific, not merely present.

Trigger Term Quality

Comprehensive natural terms users would actually say: 'MongoDB', 'schema', 'slow query', 'indexes', 'aggregation pipelines', 'sharding', 'replication', 'transactions', 'profiler', plus synonyms ('data modeling', 'monitoring', 'embed vs reference'). Anchor 4 would require missing natural terms, and none of the common MongoDB task phrases are absent.

Distinctiveness Conflict Risk

A clear niche ('MongoDB') with distinctive triggers such as 'ESR rule', 'mongostat', 'shard keys', and 'write/read concern' that no generic or adjacent skill would claim — minimal conflict risk.