Conciseness

The body is compact, assumes Claude's competence (no explanation of what LCP, INP, or hydration are), and uses terse bullets like 'TTFB contributors and redirect chains'. It is not level 5 because the 'Use This Skill When' section restates the frontmatter triggers and 'Use forward-slash paths only' / 'Avoid OS-specific command syntax' are quasi-generic rules that could be trimmed; it is well above level 3 since nothing over-explains known concepts.

Actionability

The Output Template is a concrete, copy-ready plan skeleton and the workflow names specific tools and focus areas ('RUM/CrUX', 'Lighthouse/WebPageTest/DevTools', 'render-blocking CSS/JS and hydration pressure'), but no executable commands or worked examples are given, and the promised 'topic-by-topic checklist and prioritization model' is delegated to playbook.md, which is absent from the bundle. Key details are therefore missing, matching anchor 3 rather than level 4's 'minor gaps'.

Workflow Clarity

The five numbered steps give a clear baseline -> prioritize -> convert -> gate -> verify sequence, with verification made explicit ('before/after checks in CI and post-release monitoring thresholds') and stop conditions required in the Experiments template. It is not level 5 because there is no feedback loop or error-recovery checkpoint (e.g., what to do when baseline field data is unavailable), and not level 3 because validation checkpoints are present rather than implicit.

Progressive Disclosure

The SKILL.md itself is a clean, concise overview with a single well-signaled one-level reference ('See playbook.md for the topic-by-topic checklist and prioritization model'), but no references/ directory exists and playbook.md is missing from the bundle, so the promised detailed layer is unreachable. A broken navigation path is a larger defect than level 4's 'minor organization gaps', placing this at level 3.

Specificity

Names the domain concretely ('Build and prioritize Core Web Vitals improvement plans for web apps with a focus on LCP, INP, and TTFB') but lists only 1-2 actions (build, prioritize), matching anchor 3. It is not level 4 because it lacks several distinct actions (no auditing, measuring, or reporting verbs), and not level 2 because the stated actions are concrete and domain-specific rather than generic.

Completeness

Explicitly answers both what ('Build and prioritize Core Web Vitals improvement plans for web apps with a focus on LCP, INP, and TTFB') and when ('Use when users mention CWV, Lighthouse, PageSpeed, performance budgets...') with concrete trigger phrases, matching the anchor-5 example pattern exactly. It is not level 4 because the 'when' clause is already fully explicit with named triggers.

Trigger Term Quality

The trigger list is rich and natural — 'CWV, Lighthouse, PageSpeed, performance budgets, render blocking, hydration, image prioritization, CDN caching/compression, CloudFront, or Next.js web performance tuning' — and includes the synonym pair 'CWV'/'Core Web Vitals'. A few common natural terms are missing (e.g., 'CLS', 'layout shift', 'site speed'), which matches anchor 4 ('a few natural terms missing') rather than level 5's comprehensive synonym coverage.

Distinctiveness Conflict Risk

It carves out a clear niche (field Core Web Vitals improvement planning) with distinct triggers (Lighthouse, PageSpeed, CloudFront, Next.js, render blocking) unlikely to fire for unrelated skills, matching anchor 5's 'clear niche with distinct triggers; minimal conflict risk'. Only slight overlap with a hypothetical generic web-performance skill, which does not rise to level 4's 'minor overlap risk'.