Lists multiple specific concrete actions: implementing integrated frontend and backend components, enforcing auth, input validation, output encoding, parameterized queries, building REST APIs with UI, connecting frontend to backend endpoints, creating end-to-end data flows, implementing CRUD operations with UI forms.

Clearly answers both 'what' (builds security-focused full-stack web apps with layered security, auth, validation, etc.) and 'when' with explicit 'Use when...' and 'Invoke for...' clauses listing specific trigger scenarios like implementing features across frontend and backend, building REST APIs with UI, full-stack feature work, etc.

Includes strong natural keywords users would say: 'full-stack', 'REST APIs', 'CRUD operations', 'UI forms', 'frontend', 'backend', 'web app development', 'authenticated API routes', 'microservices', 'real-time features', 'monorepo architecture'. Good coverage of terms a developer would naturally use.

Explicitly distinguishes itself from frontend-only, backend-only, or API-only skills, and carves out a clear niche as the skill that simultaneously addresses frontend, backend, and security perspectives. The security-focused full-stack framing is distinctive and reduces conflict risk.

Generally efficient but has some unnecessary verbosity—the constraints section restates things Claude already knows (e.g., 'prevent SQL injection', 'prevent XSS' after already showing parameterized queries and output sanitization). The MUST NOT list largely mirrors the MUST DO list in negative form. However, the reference table and example are well-structured and earn their tokens.

The three-perspective example provides fully executable Python and TypeScript code with concrete patterns (parameterized queries, auth dependencies, explicit response schemas, client-side guards). The security annotations explain specific defensive choices. The workflow steps and reference table give clear, concrete guidance on what to do and when.

The core workflow has a clear 6-step sequence with a security checkpoint before coding, which is good. However, there are no explicit validation/verification steps after implementation—step 5 says 'testing each component as you go' but doesn't specify how to validate or what constitutes passing. For a skill involving security-critical operations across multiple layers, the lack of a concrete verification step (e.g., run security checklist again post-implementation) is a gap.

Excellent progressive disclosure with a well-organized reference table that clearly signals when to load each reference file. The main SKILL.md serves as a concise overview with the three-perspective example inline (appropriately, as it's the core teaching), while detailed guidance is deferred to one-level-deep reference files with clear 'Load When' conditions.