Conciseness

The Check/Fix sections are tight and imperative, but the opening paragraph ("A broken image shows an ugly placeholder icon, breaks visual layouts, and communicates that the site is poorly maintained...") is re-explained nearly verbatim in the Explain section, duplicating UX rationale Claude already knows. This matches the score-3 anchor (mostly efficient with some unnecessary explanation that could be tightened); it is not 2 because the operational sections carry no padding, and not 4 because the intro/Explain duplication is a full redundant section rather than a minor trim.

Actionability

The Fix section gives a copy-paste-ready handler — onerror="this.src='/images/fallback.png'; this.onerror=null;" — plus concrete numbered remedies per scenario (wrong path, missing asset, framework onError callback, self-hosting external images), and Quick Reference names a concrete verification method (DevTools Network tab, blocked requests). This fits the score-4 anchor (mostly executable guidance with minor gaps); not 5 because detection code and the CI check live only in the reference file, so the body alone is not fully self-sufficient for execution.

Workflow Clarity

The body sequences Check (scan and identify broken images with numbered categories) → Fix (numbered remediation) → verify ("Test with DevTools Network tab blocked requests to verify fallback behaviour"), a clear sequence with an explicit validation checkpoint matching the score-4 anchor. Not 5 because there is no explicit re-check loop after fixing (e.g., re-run the scan/build check to confirm zero broken images), which the score-5 anchor's feedback-loop pattern expects.

Progressive Disclosure

The 45-line body is well-organized into Quick Reference / Check / Fix / Explain / Code Review sections and ends with a clearly signaled, one-level-deep pointer — "For full implementation details, code examples, and framework-specific guidance, see references/rule.md" — which resolves to a real file containing the code examples, framework guidance, and verification steps. This matches the score-5 anchor (clear overview with well-signaled one-level-deep references, content appropriately split, easy navigation), and the simple-skill note allows 5 for a short, well-organized single-purpose skill.

Specificity

The description lists several concrete actions — "Check encoded size, rendered size, loading strategy, and above-the-fold impact together" and "reviewing image assets, markup, and CDN or build transforms" — which matches the score-4 anchor (several specific actions, minor gaps). It falls short of 5 because the enumerated checks (encoded size, loading strategy, above-the-fold) describe image-optimization concerns rather than the skill's actual broken-image scope (detect 404s, add onerror fallbacks), leaving a coverage gap.

Completeness

Both parts are explicitly present: the 'when' ("Use when reviewing image assets, markup, and CDN or build transforms related to Fix broken images") and the 'what' ("Check encoded size, rendered size, loading strategy, and above-the-fold impact together"), matching the score-4 anchor. Not 5 because the 'what' clause does not actually describe what the skill body does — it reads like generic image-optimization copy-pasted from a sibling rule — and the 'when' phrasing ('related to Fix broken images') is awkward rather than a crisp trigger phrase.

Trigger Term Quality

Natural terms a user would say are present — "broken images", "image assets", "markup", "CDN", "build transforms" — giving good keyword coverage per the score-4 anchor. It misses common variations like "404 images", "missing images", "image fallback", or "onerror" that would warrant a 5.

Distinctiveness Conflict Risk

The trigger "reviewing image assets, markup, and CDN or build transforms" plus checks like "encoded size, rendered size, loading strategy, above-the-fold impact" overlap heavily with image-optimization skills (next-gen formats, lazy loading, responsive images), fitting the score-3 anchor (somewhat specific but can still overlap with similar skills). The "broken images" phrase provides some niche, so it is above 2, but a description this generic about image/CDN review would fire for the wrong image skills too often to score 4.