Conciseness

The 33-line body is lean and every sentence earns its place: scope categories are defined by detection criteria ("A database query inside a loop that should be one batched query") rather than tutorial explanations, and it assumes Claude already knows what N+1 queries or pagination are. It matches anchor 5 ('lean and efficient; assumes Claude's competence') and not anchor 4, which would require over-explanation that could be trimmed — none is evident.

Actionability

As an instruction-only skill, the guidance is concrete and complete: five scope categories each with concrete manifestations ("caches without eviction, and string concatenation in loops"), a concrete calibration method ("Count iterations against the expected data size... Read the AGENTS.md or CLAUDE.md chain"), an explicit exclusion list ("caching suggestions without evidence", "for versus forEach"), and a required reporting format ("Name the loop or path... State the realistic data size... Give the fix"). This covers the common cases fully, matching anchor 5; anchor 4's 'minor gaps' does not apply, and per the scoring notes the absence of code is not penalized for instruction-only skills when the guidance is this actionable.

Workflow Clarity

The workflow is coherently sequenced: identify loops and per-request paths, calibrate iteration counts against confirmed data sizes and consult the AGENTS.md/CLAUDE.md chain for expected scale, apply the threshold filter ("Drop findings that depend on data sizes you cannot confirm"), then report in the specified format. This is a simple single-purpose skill under 50 lines where the action is unambiguous, and the threshold section functions as an explicit checkpoint, so the simple-skill exception for a 5 applies; anchor 4 would require missing checkpoints that are not missing.

Progressive Disclosure

No bundle files exist (no references/, scripts/, or assets/ directories) and none are needed: the body is well-organized into four clearly labeled sections (Scope, Method, Threshold, Reporting) and stays under 50 lines. Per the rubric guideline, a short skill with no need for external references scores 5 with just well-organized sections; the AGENTS.md/CLAUDE.md mentions are runtime pointers into the reviewed repository, not skill-bundle references.

Specificity

The description names the concrete action ("Review a code change for production-observable performance problems") and lists five specific problem categories ("N+1 queries, unbounded memory growth, missing pagination, hot-path allocations, and blocking I/O in async contexts"), which is comprehensive coverage of the domain. It matches the anchor 'lists multiple specific concrete actions; comprehensive coverage' and not the anchor 4, which requires minor gaps in coverage.

Completeness

Both questions are answered explicitly: the 'what' ("Review a code change for production-observable performance problems, including...") and the 'when' ("Use when reviewing for runtime performance, query efficiency, memory use, or scalability at expected load"). This clearly matches anchor 5, which requires both what and when with concrete trigger phrases; anchor 4 is ruled out because the 'when' clause is explicit and specific, not merely present.

Trigger Term Quality

Trigger phrases include "reviewing for runtime performance, query efficiency, memory use, or scalability" — good, natural keyword coverage. A few common variations users would say are missing (e.g., "slow", "latency", "throughput", "profiling"), so it fits 'good keyword coverage; a few natural terms missing' rather than the comprehensive anchor 5.

Distinctiveness Conflict Risk

It carves out a clear niche (production-observable performance problems in code changes) with distinct, performance-specific triggers, minimizing conflict with general code-review or other review-lens skills. The trigger clause is qualified to performance concerns ("runtime performance, query efficiency, memory use, or scalability"), so it does not match the anchor 4 case of minor overlap risk with closely related skills.