Conciseness

The intro paragraph and the entire 'Explain' section re-teach CLS basics Claude already knows ('a Core Web Vitals metric', 'Browsers derive aspect-ratio from these attributes'), and the 'Quick Reference' bullets plus the 'Code Review' section largely duplicate the Check/Fix content. There are several unnecessary explanation and padded sections, matching anchor 2 rather than anchor 3's mostly-efficient-with-minor-excess profile.

Actionability

The Fix section gives numbered, executable steps with concrete values ('width="800" height="450"', 'CSS max-width: 100% and height: auto', 'CSS aspect-ratio property as a fallback') and Check specifies scanning <img> and <picture>/<source> with file-path-and-line reporting. Minor gaps: no before/after HTML snippet inline (deferred to references/rule.md) and no DevTools verification command, so it stops short of fully copy-paste-ready coverage.

Workflow Clarity

The Check-then-Fix sequence is clearly ordered with exemption criteria and skip conditions, but validation is only vaguely referenced ('describe how to confirm the fix in DevTools') with no concrete checkpoint such as re-measuring CLS or inspecting the reserved aspect-ratio. This matches anchor 3: steps present but verification checkpoints missing or implicit, not anchor 4's mostly-present checkpoints.

Progressive Disclosure

The ~35-line body is cleanly sectioned (Quick Reference, Check, Fix, Explain, Code Review) and ends with a single clearly-signaled, one-level-deep pointer ('see references/rule.md') that resolves to a real 193-line reference file. Per the simple-skill guidance, this is well-organized with easy navigation, matching anchor 5.

Specificity

The description lists several concrete actions ('Check encoded size, rendered size, loading strategy, and above-the-fold impact together. Separate real CLS risks from tiny decorative SVGs'), but embeds the rule title awkwardly ('related to Set explicit width and height on images') and stretches coverage into adjacent image-optimization concerns, leaving minor gaps. It exceeds anchor 3 (only 1-2 concrete actions) but falls short of anchor 5's comprehensive, tightly-scoped coverage.

Completeness

It explicitly answers both: what ('Check encoded size, rendered size, loading strategy, and above-the-fold impact together. Separate real CLS risks from tiny decorative SVGs') and when ('Use when reviewing image assets, markup, and CDN or build transforms'). Both what and when are present with concrete trigger phrases, matching the anchor 5 example structure.

Trigger Term Quality

Good keyword coverage including 'image assets', 'markup', 'CDN or build transforms', 'CLS', and 'width and height', which match phrases users would naturally say. Common variations like 'image size', 'layout shift', 'aspect ratio', and 'Core Web Vitals' are missing, keeping it below the comprehensive synonym coverage of anchor 5.

Distinctiveness Conflict Risk

The CLS/image-dimensions niche is mostly distinct with specific triggers ('tiny decorative SVGs', 'CLS risks'), but the broad opening ('image assets, markup, and CDN or build transforms') creates minor overlap risk with closely related image-optimization skills. It is more distinct than anchor 3's generic overlap but lacks the fully clear niche of anchor 5.