Names the domain (REST API development for Phoenix) and mentions actions (adding, modifying, reviewing endpoints), but doesn't list specific concrete actions like defining route handlers, adding validation, writing OpenAPI specs, etc.

Clearly answers both 'what' (REST API development for Phoenix) and 'when' (Use when adding, modifying, or reviewing endpoints in the specific directory path), with an explicit 'Use when...' clause and concrete triggers.

Includes relevant terms like 'REST API', 'endpoints', 'Phoenix', and the specific file path, but misses common variations users might say such as 'routes', 'HTTP', 'API routes', 'controller', 'request handler', or 'v1 API'.

Highly distinctive due to the specific framework (Phoenix), specific concern (REST API), and specific file path (src/phoenix/server/api/routers/v1/), making it very unlikely to conflict with other skills.

Every token earns its place. No unnecessary explanations of what REST APIs are or how Phoenix works. The checklist is tight and specific, and the reference table is minimal but complete.

Provides specific, concrete commands (`make openapi`, `make lint-python`), exact file paths, exact variable names for test helper lists, and specific formatting conventions (`fake-id-{}`, `test-tag`). This is copy-paste ready guidance.

The checklist is clearly sequenced (regenerate schema → register in tests → lint), with explicit validation steps (make lint-python) and specific instructions for categorizing endpoints. For this type of task (endpoint changes), the workflow is complete with appropriate checkpoints.

Clean overview with a well-organized reference table pointing to one-level-deep files for detailed patterns. The SKILL.md stays concise while clearly signaling when to consult each reference file. However, no bundle files were provided to verify the references actually exist, but the structure itself is exemplary.