Conciseness

Nearly all content is non-obvious domain knowledge (SDK v3 API shapes, MCP preconditions, gateway session semantics), but the same critical warnings are repeated three to five times across sections — accessKey≠login session (Common mistakes, Parameter map, Quick Start comments, auth gate), anonymous-login-disabled (five places), deprecated getLoginState (four places), and the verifyOtp closure form (three places). This is 'mostly efficient but could be tightened' (anchor 3) rather than 2, since the redundancy is duplication of unique gotchas, not explanation of concepts Claude already knows.

Actionability

The cookbook is fully executable and copy-paste ready, covering all common cases: cloudbase.init, signInWithPassword, signUp + data.verifyOtp, signInWithOtp, resetPasswordForEmail + updateUser, getSession, onAuthStateChange, signOut, and the auth gate — plus exact MCP invocations like queryAppAuth(action="listProviders") and manageAppAuth(action="ensurePublishableKey"). Matches anchor 5 (copy-paste ready, common cases covered).

Workflow Clarity

The Activation Contract sequences when to use the skill relative to auth-tool-cloudbase; Prerequisites order the validation steps (check providers, then getPublishableKey, falling back to ensurePublishableKey if empty, then persist to .env.local); error feedback loops are explicit ('If it is empty, call manageAppAuth...', 'seeing that error means the callback form was skipped'); and the Completion Bar provides a pre-done checklist. This matches anchor 5 (explicit validation steps, feedback loops, checklist); the destructive/batch cap does not apply since auth flows are not batch operations.

Progressive Disclosure

The single bundle file references/extended-guide.md exists, is one level deep (verified: no nested references inside it), and is clearly signaled both in the 'Extended guide' section and the 'Reference index'. Good structure with most content appropriately placed; not 5 because the 220-line body inlines substantial material (the 15-bullet gotchas list, the full parameter map, the complete cookbook) that could partially live in the extended guide, making SKILL.md denser than an overview.

Specificity

Names the domain ('CloudBase Web Authentication') and a couple of concrete areas ('multiple login methods', 'complete user management'), but 'Provides concise and practical Web authentication solutions' is filler and concrete actions like sign-in, registration, session handling, or route guards are absent. This matches anchor 3 (domain plus 1-2 concrete actions, not comprehensive) rather than 4, which requires several specific actions.

Completeness

The 'what' is reasonably clear (Web authentication solutions with login methods and user management), but the only 'when' guidance is the ordering constraint 'after auth-tool has already been checked' — there is no explicit 'Use when...' trigger clause, which caps completeness at 3 per the judging guidelines. Not 4 because the trigger conditions for activation are not stated at all.

Trigger Term Quality

Includes some natural terms users would say ('Web authentication', 'login methods', 'user management', 'frontend integration'), but misses common variations and synonyms such as sign in, sign up, register, session, protected routes, or '@cloudbase/js-sdk'. Anchor 3 (some relevant keywords, missing variations) fits better than 4, which expects good coverage with only a few gaps.

Distinctiveness Conflict Risk

The niche is clear — CloudBase Web frontend auth explicitly positioned 'after auth-tool has already been checked' — making it mostly distinct from the sibling provider-setup skill with only minor overlap risk. Not 5 because the description does not state negative scope (e.g., not for mini program, native app, or server-side auth), leaving some conflict risk with closely related CloudBase skills.