Conciseness

The body is dense and mostly non-padded, but activation guidance is stated three times (frontmatter description, "Purpose and activation" trigger list, and "Routing Boundary"), and sections like "Tooling and portability" enumerate tools Claude already knows (pprof, perf, Lighthouse, OpenTelemetry). This matches the 'mostly efficient but includes some unnecessary explanation or could be tightened' anchor; it is not the 4 anchor because the redundancy across activation sections is more than minor.

Actionability

Concrete, executable guidance is prevalent: exact commands (`EXPLAIN (ANALYZE, BUFFERS)`, `pg_stat_statements`), a symptom-to-investigation pattern table, a required output contract with a defined table schema, and specific directives (define SLO, capture p50/p95/p99, classify observations as Verified/Likely/Hypothesis). Some directives remain abstract ("Rank hypotheses by expected user impact, confidence, reversibility"), so it fits the 'mostly executable guidance with minor gaps' anchor rather than fully copy-paste-ready at 5.

Workflow Clarity

The five-step workflow (frame/baseline, locate limiting resource, inspect layers, design/implement, benchmark/validate/roll out) has explicit validation checkpoints: re-measure after every material change, evidence classification with confidence labels, a completion checklist, before/after benchmark criteria, and predefined abort thresholds with rollback. This matches the 5 anchor's clear sequence with explicit validation steps, feedback loops, and a checklist for a complex process.

Progressive Disclosure

Domain detail is appropriately split into five well-signaled, one-level-deep reference files that all exist in the bundle (e.g. "Read [database-and-cache.md](references/database-and-cache.md)"), matching good structure. However, the "Required packaged policies" section links nine `shared/base/*.md` files plus `shared/workflow-contract.md` that do not exist in the bundle, and `scripts/validate_scenarios.py` is present but never referenced — organization gaps that keep this below the 5 anchor's 'clear overview with well-signaled references'.

Specificity

"Measure, diagnose, and improve" names three concrete actions, and the objective space is comprehensively enumerated ("latency, throughput, CPU, memory, scalability, or cost") with an explicit correctness constraint ("without regressing correctness"). This matches the anchor for multiple specific concrete actions with comprehensive coverage, exceeding the 4 anchor which only expects several actions with minor gaps.

Completeness

Both parts are present: the what ("Measure, diagnose, and improve a performance or capacity objective ... without regressing correctness") and an explicit when ("Use when performance is the primary requested outcome") plus a do-not-use boundary. The when-clause is a condition rather than concrete user trigger phrases (e.g. "optimize performance", "why is this slow"), so it fits the 4 anchor ('when' could be more explicit or specific) rather than the 5 anchor requiring concrete trigger phrases.

Trigger Term Quality

Natural keywords present include performance, latency, throughput, CPU, memory, scalability, and cost, which users commonly say. However, frequent natural phrasings like "optimize", "profile", "speed up", "slow", "benchmark", and "response time" are absent from the description, matching the 'good keyword coverage; a few natural terms missing' anchor rather than the comprehensive-synonyms anchor at 5.

Distinctiveness Conflict Risk

The description carves a clear niche (measured performance/capacity improvement) and explicitly excludes adjacent skills ("Do not use for generic code cleanup or an unmeasured incident postmortem"), which sharply reduces overlap with refactoring, debugging, and postmortem skills. This matches the clear-niche/minimal-conflict anchor at 5; the 4 anchor's 'minor overlap risk' is already addressed by the explicit exclusions.