Conciseness

The opening paragraph explains concepts Claude already knows ("they are untyped string substitutions that the browser cannot interpolate during transitions or animations"), and the Quick Reference bullets substantially repeat that intro. It is not 4 because the redundant conceptual explanation plus the intro/Quick-Reference overlap is more than minor trimming, and not 2 because the body is short and otherwise on-task with little padding.

Actionability

Concrete field-level guidance exists ("Include the correct syntax descriptor, an initial-value, and the appropriate inherits value") and specific flag conditions ("flag any @property registration that is missing initial-value"), but the body contains no executable @property code example at all — every code sample is deferred to references/rule.md. It is not 4 because a CSS implementation skill should show at least one registration snippet inline, and not 2 because the checks name specific, actionable criteria rather than high-level hints.

Workflow Clarity

A coherent Check → Fix → Explain → Code Review sequence exists with per-step instructions, but no validation checkpoint appears anywhere (e.g., verifying the transition now animates or that the registration parses). This matches 'steps listed but validation gaps; checkpoints missing or implicit'. It is not 4 because checkpoints are wholly absent rather than minor gaps, and not 2 because the sequence is well-defined with specific step content.

Progressive Disclosure

The ~30-line body is a clear, well-organized overview (Quick Reference, Check, Fix, Explain, Code Review) with a single clearly-signaled, one-level-deep pointer — "For full implementation details, code examples, and framework-specific guidance, see `references/rule.md`" — and that file exists (194 lines of details). Content is appropriately split and navigation is easy, matching the top anchor and the under-50-line simple-skill guidance.

Specificity

The description names three distinct concrete capability areas — "implementing animated gradients", "complex CSS transitions that involve custom property values", and "building a typed design token system where custom property misuse should produce visible errors" — which is several specific items with minor coverage gaps. It is not 5 because it lists trigger scenarios rather than the skill's own concrete actions, and not 3 because coverage goes beyond 1-2 actions.

Completeness

Only the "when" is present ("Use when implementing animated gradients, complex CSS transitions... or building a typed design token system") while the "what" is absent — the description never states what the skill actually does (register custom properties with @property? audit CSS? fix transitions?). This matches the anchor 'only when is present without what' exactly. It is not 3 because that anchor requires a clear 'what', and not 1 because the 'when' clause is specific and concrete rather than extremely vague.

Trigger Term Quality

Natural phrases like "animated gradients", "CSS transitions", "custom property values", and "typed design token system" are terms a frontend developer would genuinely say. It is not 5 because common synonyms are missing — notably "CSS variables" (the most common user phrasing for custom properties), "@property" itself, and "Houdini" — and not 3 because the present keyword coverage is good, not merely partial.

Distinctiveness Conflict Risk

The @property registration niche is well-defined with distinct triggers (animated gradients, custom-property transitions, typed tokens), giving mostly distinct behavior. It is not 5 because "building a typed design token system" overlaps with general design-token skills, and not 3 because the niche is far more specific than the 'somewhat specific' anchor.