Conciseness

The body is lean — imperative bullets, no explanation of concepts Claude already knows (React, Tailwind, what a component library is), and a tight ~100 lines. It is not a 5 because there is minor redundancy: 'Component discovery' and 'Primitive Guidance' both restate that every primitive has a guide at `references/primitives/<name>.md`, and 'Critical usage rules' and 'Output Checklist' overlap on accessibility and composition invariants.

Actionability

Concrete, executable guidance dominates: a copy-paste CLI command (`npx shadcn@latest add @coss/<component>`), exact file paths (`apps/ui/registry/default/particles/p-<name>-<N>.tsx`), and per-topic rule files named with one-line descriptions. It falls short of fully executable (5) because the manual-install pattern stays high-level ('install dependencies listed in the component docs page... copy required component file(s)') and the body includes no minimal inline usage snippet, leaving a small gap before the reader reaches a reference file.

Workflow Clarity

The 'Usage workflow' is a clear 6-step sequence (intent → registry lookup → select → check a particle example → write → self-check) with a validation checkpoint in step 6 and an explicit pre-return 'Output Checklist'. It is not a 5 because there is no error-recovery feedback loop — e.g., what to do when a step fails or docs and code disagree — only the forward-looking 'verify against component docs first' rule; the destructive/batch cap does not apply since this skill produces code rather than performing batch operations.

Progressive Disclosure

The body is a genuine overview that defers all detail to well-signaled, one-level-deep references, and every referenced file exists in the bundle: 4 rule files under references/rules/, portal-props.md, cli.md, component-registry.md, and all 53 primitive guides claimed (including the 6 named high-risk ones); component-registry.md serves as a flat index into the primitive guides, so navigation is easy and nothing is nested two-plus levels deep.

Specificity

Multiple concrete actions are enumerated — 'implement coss UI components', 'migrating from shadcn/Radix to coss/Base UI', 'composing trigger-based overlays', 'troubleshooting coss component behavior' — plus concrete coverage areas ('imports, accessibility, Tailwind styling, and common pitfalls'). This matches the anchor for multiple specific concrete actions with comprehensive coverage of the domain; it is not score 4 because no meaningful capability area of the skill is left unlisted.

Completeness

Both questions are explicitly answered: what ('Helps implement coss UI components correctly... Covers imports, accessibility, Tailwind styling, and common pitfalls') and when ('Use when building UIs with coss primitives..., migrating..., composing trigger-based overlays, or troubleshooting coss component behavior'). The 'when' clause lists four concrete trigger scenarios, matching the top anchor exactly.

Trigger Term Quality

Good natural-term coverage: 'buttons, dialogs, selects, forms, menus, tabs, inputs, toasts', 'migrating from shadcn/Radix', 'Tailwind styling' are phrases users would naturally say. It falls short of the comprehensive anchor (5) because common synonyms users plausibly say — 'modal', 'dropdown', 'popover', 'tooltip', 'combobox' — are absent (only covered abstractly as 'trigger-based overlays').

Distinctiveness Conflict Risk

The description is anchored to a named niche library ('coss', 'coss/Base UI') with migration direction explicitly stated ('from shadcn/Radix to coss/Base UI'), giving it a clear niche with distinct triggers and minimal conflict risk. The only conceivable overlap — a user merely working in shadcn — is disambiguated by the explicit migration direction.