Extremely lean — no unnecessary explanations, every line carries actionable information. Assumes Claude knows what REST APIs, linting, and OpenAPI schemas are.

Provides specific commands (`make openapi`, `make lint-python`), exact file paths, exact variable names for test helper lists, and concrete path format conventions (`fake-id-{}`, `test-tag`). Fully actionable without ambiguity.

The checklist is clearly sequenced (regenerate schema → register in test helpers → lint), with an explicit validation step (lint before committing). The sub-steps for test registration include a clear decision tree (GET vs Admin vs write). For a non-destructive workflow this is thorough.

Clean overview with a well-organized reference table pointing to one-level-deep files for endpoint patterns, OpenAPI codegen, and testing patterns. Content is appropriately split between the skill body and references.

Names the domain (REST API development for Phoenix) and some actions (adding, modifying, reviewing endpoints), but doesn't list specific concrete actions like defining route handlers, setting up middleware, writing request validation, 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 a concrete file path trigger.

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

The description is highly specific to a particular framework (Phoenix), a particular type of work (REST API), and a specific directory path (src/phoenix/server/api/routers/v1/), making it very unlikely to conflict with other skills.