Lists multiple specific concrete actions: 'thin HTTP routes', 'pure service logic', 'isolated data access'. Also describes specific anti-patterns to address like 'route handlers contain database queries' and 'business logic mixed with HTTP parsing'.

Clearly answers both what ('Enforce strict three-layer architecture: thin HTTP routes, pure service logic, isolated data access') and when with explicit 'Use when' clause listing five specific trigger scenarios.

Excellent coverage of natural terms: 'web API', 'route handlers', 'database queries', 'business logic', 'HTTP parsing', 'req/res', 'error handling', 'test logic', 'server'. These are terms developers would naturally use when discussing architecture problems.

Highly distinctive with clear niche around three-layer architecture for web APIs. The specific anti-patterns mentioned (req/res in services, database queries in routes) create unique triggers unlikely to conflict with general coding or other architecture skills.

The skill is comprehensive but somewhat verbose. The table format is efficient, but some patterns repeat similar concepts (e.g., the 'BAD/GOOD' examples could be tighter). The explanatory text like 'Why this matters' adds value but could be condensed.

Excellent executable code examples throughout. Every pattern includes complete, copy-paste ready TypeScript code with clear BAD/GOOD comparisons. The error handling, repository, and dependency injection patterns are fully implementable.

Clear three-layer architecture with explicit responsibilities table. The validation pattern explicitly shows two-level validation flow. The checklist at the end provides verification steps. Error mapping workflow is clearly sequenced with re-throw guidance.

Well-structured with clear sections progressing from architecture overview to specific patterns to file organization to checklist. References to verifiers at the end provide one-level-deep navigation. Content is appropriately organized without being monolithic.