Conciseness

Roughly 50 lean lines where nearly every statement is repo-specific knowledge Claude cannot already have (import sources, BUILD.gn targets, file naming conventions). There is no padding or explanation of known concepts; the few definitional lines ("Use unit tests for isolated testing of…") double as the default-choice decision rule, so every token earns its place.

Actionability

Concrete and executable throughout: exact import paths ("import {describe, it} from '../conductor/mocha-interface.js'"), exact locations ("front_end/ with .test.api.ts extension", "test/e2e/"), and exact BUILD targets ("devtools_api_test_module("api_tests")"). Minor gaps keep it below anchor 5: no complete sample test file, no rule for choosing between devtools_ui_module and devtests_foundation_module, and the E2E BUILD.gn sentence is convoluted.

Workflow Clarity

The decision workflow is unambiguous: an explicit default ("The vast majority of tests in DevTools should be unit tests") with clear escalation signals for API and E2E, and a consistent per-suite structure (When to use / Location / Test functions / BUILD.gn). Verification (running tests, linters) is explicitly delegated to the devtools-verification skill via the NOTE, and no destructive/batch cap applies.

Progressive Disclosure

The skill is under 50 lines with no need for external bundle files (none exist, and none are needed), and the content is well organized into three clearly parallel suite sections with a clearly signaled cross-skill pointer. Under the simple-skill guideline this matches anchor 5.

Specificity

"Guidance on selecting the appropriate test suite (Unit, API, or E2E tests)" names the domain and one concrete action with the three suite types enumerated, but it does not list several distinct actions. It clearly exceeds anchor 2 (the action is concrete, not generic) but falls short of anchor 4, which requires a list of several specific actions.

Completeness

Both parts are explicitly present: a clear what ("Guidance on selecting the appropriate test suite (Unit, API, or E2E tests) when writing new tests in Chrome DevTools") and an explicit when ("MUST be used when writing new tests"). Not anchor 5 because the trigger rests on a single phrasing without the multiple concrete trigger variations of the 5 example, though it is well above the weak/missing-when case of anchor 3.

Trigger Term Quality

Natural phrases like "writing new tests", "test suite", and "Unit, API, or E2E tests" give good keyword coverage, and enumerating all three suite types captures how users name tests. Common variations (e.g. "adding tests", "test coverage") are missing, so it does not reach anchor 5's comprehensive synonym coverage.

Distinctiveness Conflict Risk

Scoping to "in Chrome DevTools" and to test-suite selection gives a clear niche with a distinct trigger. Minor overlap risk remains with the closely related devtools-verification skill and with the somewhat broad "writing new tests" trigger, so it fits anchor 4 rather than anchor 5's minimal-conflict profile.