The body is dense and assumes Claude's competence — install commands, handler authoring, an HttpResponse-helpers table, browser/node setup, lifecycle table, per-test overrides, CI, anti-patterns, and limitations — with no padding explaining what MSW or Service Workers are; nearly every token earns its place.

Multiple complete, copy-paste-ready code blocks (`npm i msw`, `npx msw init public/`, full handlers.js/browser.js/node.js, vitest.setup.js lifecycle, a per-test override test, and CI yaml) use the real `http.*`/`HttpResponse` API with no pseudocode, matching the score-3 anchor.

The test lifecycle is sequenced explicitly (listen beforeAll → resetHandlers afterEach → close afterAll) in a When/Purpose table, with the per-test override→reset pattern shown end-to-end; `onUnhandledRequest: 'error'` acts as an explicit validation checkpoint that fails the test on unhandled requests.

With no bundle files present, the single ~213-line SKILL.md is organized into clearly labeled sections (Overview, When to use, Install, Authoring handlers, Browser/Node setup, Per-test overrides, CI, Anti-patterns, Limitations, References) and references only one external, one-level-deep link ([msw-getting-started][gs]); per the rubric's simple-skill note, well-organized sections warrant a 3.

Lists multiple concrete actions with named APIs — 'Authors Mock Service Worker (MSW) request handlers', 'wires them via setupWorker (browser) or setupServer (Node)', 'manages the test lifecycle (server.listen / resetHandlers / close)' — matching the score-3 anchor for multiple specific concrete actions.

Explicitly answers both what (authoring/wiring/managing handlers) and when via a clear 'Use when the project uses JavaScript / TypeScript and needs to mock fetch / XHR at the network layer for both Vitest / Jest unit tests and Cypress / Playwright integration tests' clause, matching the score-3 anchor.

Natural user-facing terms appear throughout — 'mock fetch / XHR at the network layer', 'Vitest / Jest unit tests', 'Cypress / Playwright integration tests', 'JavaScript / TypeScript' — covering the frameworks and phrases a user would actually say when needing network mocking for tests.

A clear niche — MSW network-layer mocking for JS/TS test environments with named frameworks — makes it unlikely to trigger for the wrong skill; the body's references to wiremock-stubs (JVM) and mountebank-imposters (multi-protocol) further sharpen the boundary.