Conciseness

The body is tight procedural prose with no padding or explanations of concepts Claude already knows — e.g., "Contamination: benchmark items, answers, or near duplicates reached training, prompt design, retrieval, tuning, or post-hoc selection" scopes exactly what to check rather than teaching what contamination is. Even guardrail lines like "A favorable score is not itself evidence of integrity" earn their tokens; there is nothing trimmable, so it matches the anchor-5 example rather than anchor 4's 'minor instances of over-explanation'.

Actionability

For an instruction-only skill the guidance is fully executable: an exact output format ("Begin with exactly one verdict line in the form `**Verdict: PASS**`"), a seven-row role-mapping table, four explicit ground-truth tests, eight named risk categories, and a numbered five-part report structure (Evidence / Impact / Minimal independence fix / Missing evidence / Residual risk). It sits above anchor 4 because there are no gaps in what to do or produce, and code absence is not penalized per the instruction-skill note.

Workflow Clarity

The audit method is a clearly numbered four-step sequence (state claim and map → check ground truth → probe independence failures → reach verdict) with explicit checkpoints and gates: "Missing provenance for data, splits, labels, prompts, evaluator selection, or scoring is **INCONCLUSIVE**, not evidence" and the PASS/FAIL/INCONCLUSIVE decision rules. The skill is read-only, so the destructive/batch validation cap does not apply, and nothing matches anchor 4's 'minor validation gaps'.

Progressive Disclosure

The single file is well organized (Route correctly / Audit method with four numbered subsections / Report) with no buried or nested references and no content that clearly belongs in a separate file — matching anchor 4's 'good structure; most content is appropriately placed'. It falls short of anchor 5 because at ~100 body lines it exceeds the simple <50-line self-contained case and provides no reference split at all, so navigation relies entirely on inline sections.

Specificity

The description names a rich domain — "an eval, benchmark, metric, A/B test, holdout, LLM-judge, or user-study claim" — but offers only one action, "Assess integrity", which fits anchor 3 ('names domain and 1-2 concrete actions, but not comprehensive'). It does not meet anchor 4, which requires several specific actions (e.g., map roles, check ground truth, probe contamination, deliver a verdict).

Completeness

Both parts are explicit: the what is "Assess integrity of an eval, benchmark, metric, A/B test, holdout, LLM-judge, or user-study claim" and the when is "when the question is whether measurement, comparison, or evidence is independent and trustworthy". This satisfies anchor 4 ('has both what and when; when could be more explicit or specific') but not anchor 5, because the when clause is a meta-condition about the question rather than concrete user trigger phrases like 'Use when the user asks whether...'.

Trigger Term Quality

Good natural keyword coverage across evaluation types ("eval, benchmark, metric, A/B test, holdout, LLM-judge, or user-study"), matching anchor 4's 'good keyword coverage; a few natural terms missing'. It is below anchor 5 because common user phrasings for this intent — 'contamination', 'data leakage', 'fair comparison', 'biased judge' — are absent.

Distinctiveness Conflict Risk

The description carves a clear niche — auditing evaluation integrity — and its scoping clause ('when the question is whether measurement, comparison, or evidence is independent and trustworthy') separates it from producing results, matching anchor 4's 'mostly distinct; minor overlap risk with closely related skills'. It is not anchor 5 because broad terms like "benchmark", "metric", and "A/B test" also appear in data-analysis and experiment-design contexts and the disambiguation rests entirely on the trailing qualifier.