Lean, dense, actionable body with no padded explanations of concepts Claude already knows; code comments are justified gotchas (visibilitychange flush ordering, closure-vs-window array trap) that each earn their place.

Fully executable throughout — install command, onINP usage, attribution decomposition, a complete Playwright test with the visibilityState-redefine flush trick, a long-task observer test, and a real CrUX curl; copy-paste ready.

Clear numbered Step 1–6 sequence with explicit checkpoints (install observer before navigation; redefine visibilityState before dispatching the event), and the anti-patterns table codifies the validate-style feedback loop (run N times, assert P75).

Self-contained single-file skill with no bundle directories; sections are well-organized (When to use, Steps, Anti-patterns, Limitations, References) and the References are one-level-deep external URLs, not nested file indirection.

Enumerates multiple concrete actions — 'decomposes input delay, processing duration, and presentation delay', 'asserts per-interaction INP budgets in Playwright', 'identifies long tasks blocking the main thread' — matching the multi-action anchor.

Explicitly states what the skill does (decompose, assert, identify) and provides an explicit 'Use when...' clause with concrete triggers, satisfying both what and when.

Includes natural user phrasings ('page feels unresponsive while LCP and CLS are green', 'form submit, modal open, route change', 'INP budget in CI') covering both symptom language and concrete interaction types.

Narrow INP niche with an explicit hand-off ('Covers interactions only: for service-worker cache-strategy latency use service-worker-tests') reduces conflict with adjacent skills.