Conciseness

Phrases like "Cache API silently drops responses over 10 MB", "Deletes are eventually consistent", and the exact Cache-Status values are non-obvious, high-value facts with essentially no explanation of concepts Claude already knows — but trimmable tokens remain: the ctx-gen house-rules preamble ("merged into the rendered skill by ctx-gen and never generated"), the trailing HTML gap comments, and a second full vary illustration inside the cacheHeaders example. These are minor instances of over-explanation/padding rather than the 'every token earns its place' ideal, so 4 not 5; it is well above the 'mostly efficient but includes some unnecessary explanation' anchor 3.

Actionability

Nearly every section gives copy-paste-ready code or commands — the full `Netlify-CDN-Cache-Control` function example, three complete `purgeCache` variants including the token-based Lambda form, an executable curl for the purge API, the `caches.open/match/put` handler with `config`, and `cacheHeaders`/`fetchWithCache` snippets — plus exact limits ("100 lookups, 20 insertions/deletions", "twice per 5s", "≤1024 chars/tag"). Only two contextual fragments (the `needsRevalidation` block, the `getCacheStatus` one-liner) lack imports/context, which keeps it at anchor 5's 'fully executable, covers common cases' rather than dropping to anchor 4's 'minor gaps' since the fragments are advanced edge cases, not the common path.

Workflow Clarity

The skill is reference-style rather than a multi-step procedure, and it sequences its single task well: 'read footguns first' → pick the header ('Reach for this') → set directives → verify on a deployed URL via Cache-Status ('repeat requests to warm one' gives an explicit feedback loop for the empty-cache case). Validation for the destructive purge operation is only implicit (the 202 status in examples) rather than an explicit 'verify the purge succeeded' checkpoint, which is the minor gap that keeps this at anchor 4 ('most checkpoints present') instead of 5; it is clearly above anchor 3's missing-checkpoints level.

Progressive Disclosure

No bundle files exist (no references/, scripts/, or assets/), so everything is inline in a well-organized single file: clearly signaled sections (Footguns, Directives, Netlify-Vary, purge, Cache API, @netlify/cache, Durable, Debugging) with the most-urgent content first and an external pointer only where appropriate (docs.netlify.com for the purge API identifier mapping). At ~330 lines, the full `@netlify/cache` API details could arguably live in a reference file, which is the 'minor organization gap' of anchor 4 — better than anchor 3's 'content that should be separate is inline' since the structure is tight and navigable, but not the clean overview-plus-references split of anchor 5.

Specificity

It lists many concrete actions — "Cache dynamic and static responses on Netlify's CDN", "tune cache TTL or stale-while-revalidate", "vary a cache key by query/header/cookie/country/language", "purge or invalidate the cache by site or cache tag", "use the programmatic Cache API (caches.open/match/put)" — which is anchor-5 comprehensiveness. However, the second-person phrasing ("Use when you add caching...") triggers the rubric's one-point voice penalty, reducing it to 4.

Completeness

The 'what' is explicit up front ("Cache dynamic and static responses on Netlify's CDN from Functions, Edge Functions, and proxies") and the 'when' is a long, concrete 'Use when...' clause enumerating a dozen specific trigger scenarios ending with debugging via the Cache-Status header. Both are explicitly and concretely answered, matching anchor 5 exactly; it is not anchor 4, where the 'when' would be less specific.

Trigger Term Quality

Natural user phrasings are covered comprehensively with synonyms: "add caching or cache-control headers", "purge or invalidate the cache", "speed up an expensive API call", "debug why a response is or isn't cached", plus jargon users actually say (TTL, stale-while-revalidate, ISR, on-demand revalidation, Cache-Status). This matches anchor 5's comprehensive synonym coverage and is clearly above anchor 4's 'a few natural terms missing'.

Distinctiveness Conflict Risk

It carves a clear niche — Netlify's CDN caching specifically — with distinct triggers (Netlify-CDN-Cache-Control, durable cache, Netlify-Vary, purgeCache, @netlify/cache helpers) that no generic performance or HTTP-caching skill would claim, so conflict risk is minimal per anchor 5. It is well above anchor 4's overlap with 'closely related skills' because the platform scoping is unambiguous.