Conciseness

The body is dense and expert-level (severity bands, the lru_cache mechanism correction, Vary edge cases) with almost no filler, but the poisoning/deception definitions and rhetorical framing like "The worst version of this is not slow, and it is not stale" restate concepts Claude already knows and could be trimmed. Not 5 for these minor over-explanations; well above 3 because nearly every paragraph carries audit-relevant decision content.

Actionability

Fully executable guidance: a copy-paste-ready cache_key() builder with design rationale, literal Vary/Cache-Control headers, a before/after worked example with actual key strings ("dashboard:1" → "s:v1:t:acme:u:1:l:en-GB:dashboard"), an ordered fix preference list, and a concrete report template. The common cases are covered end to end.

Workflow Clarity

A numbered six-step derivation with an explicit checkpoint ("Check the tier"), verification-gated classification ("Downgrade to informational only after confirming identifiers are globally unique"), and mandated validation ("A key fix with no test that exercises two distinct principals against the same slot is not finished"). Not 4 because the validation checkpoints are explicit and the test-first closing rule closes the loop.

Progressive Disclosure

Both bundle files exist, are one level deep, and are clearly signaled with purpose statements ("Full mechanism and Python-doc citations: references/lru-cache-trap.md"; "Full RFC and OWASP citations: references/http-cache-directives.md") — the verbatim spec-quote bulk is correctly moved out of the body while usable summaries stay inline. Headers make the 350-line body easy to navigate, and the split is appropriate for an audit procedure.

Specificity

"Checks the key holds every value the response depends on (tenant, user, scope, locale), writes the fixed key, Vary header and tests" names several concrete actions with specific artifacts. Not 5 because it omits the severity triage and reporting activities that are a substantial part of what the skill does.

Completeness

Explicitly answers when ("Use whenever a user saw another user's or tenant's data, or a per-user response goes through a shared cache, Redis or a CDN, or a cache key is designed or changed") and what ("Checks the key holds every value… writes the fixed key, Vary header and tests") with concrete trigger phrases. A 4 would require the when-clause to be less explicit, which it is not.

Trigger Term Quality

"user saw another user's or tenant's data", "shared cache, Redis or a CDN", and "cache key" are natural phrases a user would say, plus named technologies. Not 5 because common synonyms like Memcached, cache poisoning, or cross-tenant leak are absent.

Distinctiveness Conflict Risk

A clear niche (cache-key discriminator auditing) with distinctive symptom triggers like "user saw another user's or tenant's data". The only breadth comes from the deliberate "cache key is designed or changed" trigger, which is minor and does not create meaningful conflict risk.