Conciseness

The body is lean and dense: every sentence instructs ("Profile in a run you do not report, because profilers and tracers slow the work down", "Run each side at least 5 times, alternating"). It names concrete tools inline (`top`, `pidstat`, `py-spy`, `perf`, `strace -c`, `uptime`, `nproc`) without explaining what they are, and never explains concepts Claude already knows. Matches the 5-anchor 'lean and efficient; every token earns its place'.

Actionability

For an instruction-only skill the guidance is fully executable: specific commands per limiter type ("node --cpu-prof", "py-spy", "strace -c on Linux"), quantitative decision rules ("at least 5 times, alternating", "A gap smaller than the run-to-run variation is no measurable difference", "Removing a piece that takes 10% of the run can make the run at most about 11% faster"), and a copy-ready report sentence. Matches the 5-anchor 'fully executable; specific examples cover the common cases'.

Workflow Clarity

The sequence is explicit: pre-run steps (write the claim, read the script, check load), the seven numbered validation questions, then a report section with explicit inconclusive criteria and fallback behavior ("If you cannot tune it, do not pick a winner from that run"). The questions are themselves validation checkpoints with error-recovery feedback loops (profile → retune → re-measure), and a fast path for ballpark requests is defined. Matches the 5-anchor 'clear sequence with explicit validation steps; feedback loops'.

Progressive Disclosure

The skill is under 50 lines, self-contained, and well-sectioned (Before you run anything / The questions / Report / Other perf material), so by the simple-skill note it approaches 5. It drops to 4 because 'Report' and 'Other perf material' depend on external material — "per the **Opening a PR** playbook", "the **Perf issue** playbook", "the **Hillclimb** playbook" — with no paths or links, and no bundle files exist to resolve them; that is a minor navigation gap, matching the 4-anchor 'references mostly clear; minor organization gaps' rather than the 5-anchor's well-signaled references.

Specificity

The description enumerates concrete vetting dimensions — "(limiter, tuning, limits, errors, repeatability, relevance, and whether the work happened)" — which is several specific facets of the single action "Vet a perf measurement ... before you report or act on it". It lists several specific actions/aspects with minor gaps (e.g., no mention of what to do with the verdict), matching the anchor 'Lists several specific actions; minor gaps' rather than the fully comprehensive 5-anchor's battery of distinct actions.

Completeness

Both halves are explicit and concrete: what — "Vet a perf measurement (limiter, tuning, limits, errors, repeatability, relevance, and whether the work happened)" — and when — "Use when you run a benchmark or report a speedup or regression you measured." This matches the 5-anchor 'clearly and explicitly answers both what AND when with concrete trigger phrases'; the 4-anchor ('when' could be more explicit) does not apply since the trigger clause is specific.

Trigger Term Quality

Natural user phrases are present: "run a benchmark", "report a speedup or regression you measured", "perf measurement". These are the words a user would naturally say when needing this skill. It is not the 5-anchor's comprehensive coverage with synonyms — common variations like "performance test", "throughput", "latency numbers", or "microbenchmark" are missing.

Distinctiveness Conflict Risk

It occupies a clear niche — vetting self-produced performance measurements before reporting — with distinct triggers (benchmark runs, speedup/regression claims) that would not fire for general perf-tuning, profiling, or code-review skills. Minimal conflict risk; matches the 5-anchor 'clear niche with distinct triggers'.