Conciseness

The body is short but spends tokens on what Claude already knows: 'Serving a 2000px image to a 400px phone screen wastes bandwidth and slows loading—srcset lets the browser download only the size it needs', plus Quick Reference bullets ('Use srcset to provide multiple image sizes', 'Browser selects optimal size based on viewport and DPR') that restate the mechanics. The Check, Fix, and Explain sections are redundant one-liners repeating the same idea. It could be meaningfully tightened, matching 'mostly efficient but includes some unnecessary explanation or could be tightened' rather than the 'minor instances' of a 4.

Actionability

The Code Review section offers some concrete guidance — 'Flag pages that always ship desktop-sized assets to mobile, omit `sizes`, or generate variants that do not match the actual rendered layout' — but the body contains no example of correct srcset/sizes markup, and the Fix section ('Implement responsive images with srcset for different screen sizes and resolutions') is a vague directive with no executable steps. Key details are deferred to references/rule.md, leaving the body incomplete.

Workflow Clarity

Check → Fix → Explain → Code Review implies a sequence, but the sections overlap (Check's 'Verify that images use srcset and sizes attributes' and Code Review's 'Inspect image markup… for `srcset`, `sizes`' say nearly the same thing) with no explicit ordering or validation checkpoints. The single action is not unambiguous — it is unclear whether this is an audit skill or an implementation skill — so the simple-skill exception to reach 5 does not apply.

Progressive Disclosure

The body is a lean overview with a clearly signaled, accurately described, one-level-deep reference: 'For full implementation details, code examples, and framework-specific guidance, see `references/rule.md`' — and that file exists and does contain the code examples. No nested references, no buried content, easy navigation.

Specificity

Concrete actions are stated — 'Check both the markup and the CSS layout' — with specific review targets ('article images, cards, galleries, or any component rendered at multiple sizes across breakpoints'). Falls short of 5 because coverage stops at reviewing: no fixing or implementing capability is stated.

Completeness

The 'when' is explicit ('Use when reviewing article images, cards, galleries…') and a 'what' exists ('Check both the markup and the CSS layout'), but the what is embedded in the when-clause rather than stated as a standalone capability, so it is not the fully explicit what+when of a 5.

Trigger Term Quality

Natural terms users would say are present: 'article images', 'cards', 'galleries', 'breakpoints', 'srcset', 'sizes'. A few common terms are missing — most notably the phrase 'responsive images' itself, plus retina/high-DPI synonyms.

Distinctiveness Conflict Risk

A clear niche — reviewing srcset/sizes behavior across breakpoints — with distinct technical triggers ('an incorrect `sizes` attribute can negate a perfectly good `srcset`'). Minor overlap risk with general image-optimization or frontend code-review skills.