Conciseness

The intro paragraph ("More than 55% of global web traffic comes from mobile devices. Mobile browsers have different rendering engines...") explains concepts Claude already knows and is duplicated verbatim in references/rule.md's 'Why It Matters' section, matching 'mostly efficient but includes some unnecessary explanation or could be tightened'. The rest of the body (Quick Reference, Check/Fix/Explain/Code Review) is lean, keeping it above the noticeably-verbose 2 anchor.

Actionability

The Quick Reference gives concrete specifics ("375px (iPhone SE), 390px (iPhone 14), 768px (iPad)", "one Android (Chrome) and one iOS (Safari)") but the core Check/Fix guidance stays high-level — "Add Playwright tests using mobile device presets" names no presets, config file, or commands, and "Check for Playwright device emulation... or notes about mobile testing" doesn't say where to look. This fits 'some concrete guidance but incomplete; missing key details' — all executable code is deferred to the reference file.

Workflow Clarity

The Check → Fix → Explain → Code Review sections form a clear, coherent sequence for this review-type skill (which is non-destructive, so the validation cap doesn't apply), and 'Quick Reference' front-loads key facts. It misses a 5 because the body has no verification checkpoint confirming the added tests actually fail-and-block regressions — that guidance lives only in references/rule.md's Verification section.

Progressive Disclosure

The body is a short, well-organized overview with a clearly signaled one-level-deep reference ("For full implementation details, code examples, and framework-specific guidance, see references/rule.md") that exists and points no further, and there are no scripts/ or assets/ bundles to organize. It falls short of the 5 anchor because content is not cleanly split — the 'why it matters' paragraph is duplicated between the body and the reference instead of living only in rule.md.

Specificity

The description enumerates several concrete review targets — "reviewing CI coverage, automated checks, or test strategy" — plus a concrete focus directive ("Focus on whether the rule is continuously verified, not just documented"), matching the 'several specific actions with minor gaps' anchor rather than the 1-2 actions of the anchor below.

Completeness

Both parts are present: an explicit "Use when reviewing..." trigger clause and a what-clause ("Focus on whether the rule is continuously verified, not just documented"). It falls short of a 5 because the what-side stops at review focus — it never states what the skill actually does (add device-preset tests, flag CI gaps) — but exceeds a 3 since the when-clause is explicit and specific.

Trigger Term Quality

Natural keywords like "CI coverage", "automated checks", "test strategy", and "real mobile devices and viewports" give good coverage, but common variations users would say — "mobile testing", "responsive", "device emulation", "Playwright" — are missing, fitting the 'good coverage, a few natural terms missing' anchor and falling short of the comprehensive-synonym anchor at 5.

Distinctiveness Conflict Risk

The mobile-specific qualifier ("Test on real mobile devices and viewports") carves a clear niche with minimal conflict risk, though the broad lead-in "CI coverage, automated checks, or test strategy" could also match general CI/testing review skills — 'mostly distinct, minor overlap risk' rather than the fully distinct niche of the 5 anchor.