Lean and efficient; assumes Claude's competence and avoids re-explaining basic concepts, while the rationale given is project-specific and non-obvious (e.g. Cognito authorizer cannot be exercised at FastAPI level).

Provides concrete executable commands ('npx playwright test --update-snapshots', 'npx playwright test') and specific file paths (docs/use-cases/UC-*.md, playwright.config), with guidance concrete enough to act on directly.

A 9-step sequenced workflow with explicit validation checkpoints (step 7 confirm Chromium-only config, step 9 run tests and confirm everything passes), plus a DO NOT section that anticipates failure modes.

Well-organized into Instructions, DO NOT, Workflow, and Resources sections with clearly signaled one-level-deep references to project docs (testing.md, design-system.md, UC-*.md); no nested-reference chains.

Lists multiple specific concrete actions — 'Writes Playwright end-to-end functional tests and visual regression baselines for a use case, and updates the use-case-to-test traceability matrix' — rather than vague language, matching the top anchor.

Explicitly answers both what (writes functional/visual regression tests, updates traceability matrix) and when (a 'Use when...' clause with concrete triggers), satisfying the top anchor.

Provides natural phrases users would say — 'write E2E tests for UC-xxx', 'add Playwright coverage', 'add a visual regression test', 'end-to-end testing', 'screenshot testing' — with good coverage of common variations.

Occupies a clear niche — Playwright E2E and visual regression for a specific use case (UC-xxx) — with distinct triggers unlikely to fire for unrelated skills.