Conciseness

The body is dense with Workbox-specific facts Claude cannot be assumed to know (recipe defaults like '60 images cached for 30 days', cache names like 'workbox-precache-v2', the __WB_MANIFEST injection constraint), so most tokens earn their place. Minor trimming opportunities: the 'CI integration' section repeats the 'Running -> In CI' commands verbatim, and the CDN workbox-sw and waiting-event caveats each appear in both the Anti-patterns table and Limitations.

Actionability

Mostly executable guidance: full copy-paste Vitest and Playwright specs, install commands, and CI YAML, plus a Step 2 table routing each assertion type to the right runner. The gap keeping it below anchor 5: the Playwright tests hit 'https://localhost:3000' with no playwright.config / webServer / baseURL setup shown, so the inline specs are not runnable as-is without project-specific wiring.

Workflow Clarity

Clear six-step authoring sequence (install deps -> decide runner placement -> manifest test -> recipe tests -> window events -> plugin gate), followed by running, result parsing, and debugging guidance. Validation and error-recovery loops are explicit: the 'Parsing results' table tells how to read failures ('When an assertion fails on the cache-content surface, also check the namespace name') and the Anti-patterns table gives failure -> why -> fix for each common trap.

Progressive Disclosure

Well-signaled one-level-deep references, both verified to exist and contain what is claimed: references/recipe-tests.md holds the other five recipe tests ('each retaining its test-invariant default') and references/cache-strategy-design.md holds the strategy-per-route table, audit, and invalidation locking. The split is sound — one representative test inline, the rest in references — and the References section indexes everything including sibling skills.

Specificity

The description enumerates five concrete actions with named APIs: 'pin behavior of the named recipes (pageCache, staticResourceCache, imageCache, googleFontsCache, offlineFallback, warmStrategyCache)', 'validate workbox-precaching manifest injection (__WB_MANIFEST revisioning)', 'assert workbox-routing route handler matches', 'assert workbox-expiration and workbox-cacheable-response plugin gates', and 'verify the workbox-window registration helper events (installed, waiting, controlling, activated)'. This matches the anchor 'Lists multiple specific concrete actions; comprehensive coverage' — the coverage spans the entire package family the skill addresses, with no gaps.

Completeness

Both questions are answered explicitly: the 'what' is the five-verb enumeration of assertions, and the 'when' is a concrete trigger clause — 'Use when a project ships (or is adopting) a Workbox service worker and its strategy choices or recipe behavior need pinning against refactors or a version upgrade.' This matches anchor 5 ('clearly and explicitly answers both what AND when with concrete trigger phrases'); the when-clause names specific scenarios rather than being merely adequate as in anchor 4.

Trigger Term Quality

Good natural-keyword coverage: 'Workbox-built service workers', 'precache', 'sw.js', 'pin behavior', 'version upgrade', 'refactors', 'TTL'. It falls short of the anchor-5 'comprehensive coverage including synonyms' because common user phrasings like 'PWA' and 'offline' are absent as trigger terms (offline only appears inside the recipe name offlineFallback). Better than anchor 3 ('missing common variations or synonyms') since multiple natural phrasings are present.

Distinctiveness Conflict Risk

A clear niche with distinct triggers: Workbox specifically, named recipes, and named packages (workbox-precaching, workbox-window, etc.). It even carves out an explicit boundary against the adjacent design-side skill — 'Cache-strategy design ... lives in references/cache-strategy-design.md' — reducing conflict risk with the closest neighboring skill. Minimal overlap with anything outside the service-worker testing niche.