Lists multiple specific concrete actions: 'Creates API route handlers', 'implements Server Actions with Zod schema validation', and 'integrates external REST APIs with error handling'. These are distinct, concrete capabilities.

Clearly answers both what ('Creates API route handlers, implements Server Actions with Zod schema validation, integrates external REST APIs with error handling') and when ('Use when adding endpoints, building request handlers, or wiring external services') with explicit trigger terms in parentheses.

Includes strong natural keywords users would say: 'endpoint', 'REST API', 'request handling', 'fetch', '.ts route files', 'endpoints', 'request handlers', 'external services'. Good coverage of terms a developer would naturally use.

Clearly scoped to API route handling, Server Actions, and REST API integration with specific technology mentions (Zod, .ts route files). This carves out a distinct niche unlikely to conflict with general coding or frontend skills.

The content is lean and efficient. It uses tables for architecture decisions, provides executable code without explaining what Next.js or Zod are, and the design rules are terse bullet points. Every section earns its place.

All three code patterns (Route Handler, Server Action, external API fetch) are fully executable TypeScript with imports, schemas, and error handling. The workflow includes a concrete curl smoke test command. Design rules specify exact response shapes and status codes.

The Quick Workflow section provides a clear 5-step sequence from file creation through validation to verification, including an explicit smoke test step. The architecture table clearly delineates when to use each pattern, preventing misuse.

There is a reference to project-specific config via `api-config.md`, which is good. However, the design rules section is fairly dense and could be split into a separate reference file. The skill is reasonably organized but the inline density of the design rules section slightly undermines progressive disclosure.