Conciseness

The ~30-line body is tight and operational (Quick Reference bullets, Check/Fix/Explain/Code Review sections), but the intro's 'localStorage is accessible to any JavaScript running on the page' is duplicated almost verbatim by Quick Reference bullet 2, and that localStorage-vs-httpOnly explanation is background Claude already knows. Not 3 because the padding is minor and localized.

Actionability

Concrete, specific guidance throughout: exact storage mechanisms ('localStorage/sessionStorage to httpOnly cookies set by the server'), exact flags ('Secure and SameSite'), exact APIs to flag ('localStorage.setItem, sessionStorage.setItem, document.cookie'), and exact HTTP methods ('POST, PUT, PATCH, and DELETE'). Not 5 because the actual implementation 'how' is entirely deferred to the reference — the body gives no code or commands of its own, and CSRF defense mechanics are only named, not shown.

Workflow Clarity

The Check → Fix → Explain → Code Review sections read as a rough review-and-remediation flow, but the sequence is never made explicit — Check and Code Review overlap without clarification of their relationship, and there are no validation checkpoints in the body (the reference's five Verification steps exist but are not surfaced or signaled). This matches anchor 3: steps present, checkpoints implicit.

Progressive Disclosure

The body is a clean overview (under 50 lines) that appropriately defers 'full implementation details, code examples, and framework-specific guidance' to references/rule.md, which exists as a real one-level-deep, clearly signaled reference. Content split is appropriate and navigation is easy.

Specificity

Names the domain ('token storage approach', 'XSS-based token theft') and lists three specific actions — 'reviewing authentication implementation', 'setting up a new auth system', 'evaluating whether the current token storage approach exposes the application'. It falls short of 5 because the core remediation capability (e.g., moving tokens to httpOnly cookies) is never stated, leaving a gap in coverage.

Completeness

'When' is explicit and detailed ('Use when reviewing... setting up... evaluating...'), but the 'what' is only implied — the description never states what the skill does (secure token storage via httpOnly cookies, CSRF defenses). It is above anchor 2 because the 'when' clauses embed a specific evaluation activity, but below anchor 4, which requires an explicit 'what' statement alongside 'when'.

Trigger Term Quality

Natural terms like 'authentication implementation', 'new auth system', 'token storage', and 'XSS-based token theft' match what users would say. Not 5 because common synonyms users plausibly mention — JWT, localStorage, cookies, session tokens — are absent.

Distinctiveness Conflict Risk

The niche (token storage XSS exposure) has distinct triggers with minimal conflict risk. Not 5 because 'reviewing authentication implementation' is broad enough to overlap with generic auth-review or security-review skills.