Conciseness

The body is compact and densely packed: a 4-bullet Quick Reference plus four tight numbered task sections with no padded prose. One introductory sentence ('Unoptimized video is frequently the single heaviest asset on a page...') explains a fact Claude already knows, which keeps it at 4 rather than 5.

Actionability

This is an instruction-only skill and the guidance is actionable with concrete specifics: 'Re-encode to multiple resolutions (e.g. 480p/720p/1080p)', 'VP9 or AV1 in WebM, or HEVC/H.264 in MP4', 'Add a poster attribute', 'Add preload="metadata" (or "none")'. Per the rubric's scoring note, absence of inline code is not penalized when guidance is actionable, but it stays at 4 because details like 'a reasonable CRF/quality setting' remain unspecified and no example command or markup appears in the body.

Workflow Clarity

A clear Check → Fix → Explain → Code Review sequence, with the Check step enumerating five verifications and the Code Review step closing the loop ('describe how to confirm the fix in DevTools' Network and Media panels'). It does not reach 5 because there is no explicit validate-and-retry checkpoint after fixes, and reporting 'grouped by severity' is stated but not operationalized.

Progressive Disclosure

The body is a well-organized overview (Quick Reference plus task sections) that appropriately defers 'full implementation details, code examples, and framework-specific guidance' to references/rule.md — a real file, clearly signaled, and one level deep with no nested references. This matches the score-5 anchor; the structure and navigation are easy to follow.

Specificity

The description lists several concrete check actions — 'Check encoded bitrate, resolution relative to the rendered player size, codec/container choice, and whether a poster/thumbnail avoids blocking on the first frame' — four specific verification actions. It stays at score 4 rather than 5 because coverage is one-sided: it only describes checking, omitting the fix/re-encode actions the skill actually performs, a minor gap in comprehensiveness.

Completeness

Both halves are explicit: 'when' is answered by 'Use when reviewing <video> elements, background/hero video, or embedded media assets' with concrete trigger phrases, and 'what' by the four enumerated checks (bitrate, resolution vs player size, codec/container, poster/thumbnail). This matches the score-5 anchor; score 4 would require the 'when' clause to be less explicit, which it is not.

Trigger Term Quality

Natural trigger phrases like '<video> elements', 'background/hero video' map well to what a user would say when they need this skill. Not score 5 because common variations are missing: no file extensions (.mp4, .webm), no 'video optimization' or 'compress video' phrasing, and 'embedded media assets' is broader than the niche.

Distinctiveness Conflict Risk

Video optimization is a mostly distinct niche with clear triggers (<video> elements, background/hero video). It stops short of 5 because 'embedded media assets' is broad enough to create minor overlap risk with audio/media-embedding or general performance skills.