Conciseness

The body is dense and directive with zero concept explanations ("Never ignore OSStatus. Every SecItemAdd... path must handle success and expected failures"), but has minor trimmable redundancy: the Review Checklist partly restates the Security Invariants, and references are listed twice (loading table plus References section). It is tighter than the anchor-3 "some unnecessary explanation" but not the every-token-earns-its-place anchor 5.

Actionability

The "Minimum Safe Keychain Write" is a complete, copy-paste-ready Swift function handling errSecSuccess, errSecDuplicateItem, and generic statuses, and the task-to-reference loading table gives exact executable routing; however, most executable patterns live in the reference files, so the body alone covers only the single most common case — anchor 4 rather than anchor 5's "specific examples cover the common cases".

Workflow Clarity

The Workflow classifies requests into three sequenced paths with an explicit validation gate before destructive action ("preserve existing data, verify the new item, then remove legacy storage only after success") and a per-item "pass, fail, or not applicable" checklist whose failures feed back into loading the domain reference and reporting severity — matching anchor 5's explicit validation, feedback loops, and checklists.

Progressive Disclosure

All 14 referenced files exist and are one level deep (verified: reference files contain only intra-file anchors and external Apple doc links, no nested .md references), navigation is a task-based loading table plus one-line purposes in the References section, and the body explicitly mandates "Do not load every reference file by default... load only the files needed by the user's task" — a clear match to anchor 5.

Specificity

"Builds or reviews Apple-platform security with Keychain, LocalAuthentication, CryptoKit, Secure Enclave, certificate pinning, key sharing, and secure credential migration" lists multiple specific concrete capabilities spanning the domain, matching the comprehensive-coverage anchor; it is well above anchor 4, which expects only several actions with minor gaps.

Completeness

The description explicitly answers what ("Builds or reviews Apple-platform security with...") and when ("Use for secrets, biometrics, cryptography, trust evaluation, or OWASP MASVS/MASTG") with concrete trigger phrases, matching the anchor-5 example structure; the missing-"Use when" cap of 3 does not apply.

Trigger Term Quality

"Use for secrets, biometrics, cryptography, trust evaluation, or OWASP MASVS/MASTG mobile controls" provides good natural keyword coverage, but common user phrasings like "Face ID", "Touch ID", "passwords", or "tokens" are absent — the anchor-5 example includes synonyms and extensions, which this lacks.

Distinctiveness Conflict Risk

"Apple-platform security" with Keychain/Secure Enclave/MASVS triggers is a clear niche, but listing "CryptoKit" and keychain work creates minor overlap risk with closely related sibling skills (the body itself routes primitive CryptoKit syntax elsewhere), fitting anchor 4 rather than the minimal-conflict anchor 5.