Conciseness

No section explains concepts Claude already knows — every block carries non-obvious, library-specific facts ("~800 KB raw is ~82 KB over the wire", the pnpm "app's Sass can only load what the app lists" constraint, the $primary turquoise-reversion pitfall, "icon fonts often outweigh Bulma itself"). The helper-prop enumeration is a concrete grep checklist, not padding. Anti-drift check against score 4 ("minor instances of over-explanation"): nothing in the body can be trimmed without losing information.

Actionability

Fully executable throughout: exact measure commands (`wc -c dist/assets/*.css`, `gzip -c dist/assets/*.css | wc -c`), a flavor table with copy-paste import strings and per-flavor raw/gzip sizes, install commands, and a complete `src/styles.scss` with exact `@use` lines including the `with ($primary: #1e6b99)` configuration. The no-helpers gate specifies exact prop names and class patterns to grep (`is-*`, `has-*`, `m*-*`, `p*-*`).

Workflow Clarity

Clear cheapest-first decision flow (3 ranked levers), explicit validation loop — "Always measure first", "Re-measure after every step... Never claim a saving without a number" — plus a hard gate ("Any hit → do not use no-helpers; fall back to no-dark-mode or Lever 2") with an error-recovery fallback path and an honest-stop checkpoint ("If the gzip number is already within the app's budget, say so and stop"). Not a destructive/batch operation, so no cap applies.

Progressive Disclosure

The body stays a lean ~130-line overview; the bulky material (full component→partial mapping, extras partial inventory, worked styles.scss) is deferred to `references/modular-build.md`, which exists, is substantive (198 lines), and is clearly one level deep. The reference is well signaled twice with a description of its contents, and version-drift-prone numbers are anchored to the "hence measure" instruction rather than stated as timeless facts.

Specificity

Quotes multiple concrete actions — "measure raw and gzip size, then apply the cheapest lever that fits (lighter prebuilt CSS flavor, hand-rolled modular Sass build, import and icon-asset hygiene)" — comprehensively covering the skill's scope. Anti-drift check against score 4 ("minor gaps in coverage"): no action in the body is absent from the description, so 5 fits best.

Completeness

Explicitly answers both questions: the "what" ("Reduce the built CSS size of an app using @allxsmith/bestax-bulma... measure raw and gzip size, then apply the cheapest lever") and a concrete "Use when..." clause listing four distinct trigger scenarios — the exact structure of the anchor-5 example.

Trigger Term Quality

Natural user phrasings — "the CSS bundle looks too big", "a size budget or Lighthouse audit flags stylesheet weight" — plus file-path triggers ("switching bestax.css to a versions/*.css flavor") and technical terms ("modular @use Bulma/Sass build"). This matches anchor 5's requirement for synonyms and file extensions; score 4 ("a few natural terms missing") would understate coverage.

Distinctiveness Conflict Risk

Niche is unambiguous — library-scoped to @allxsmith/bestax-bulma with triggers (bestax.css flavors, versions/*.css, modular @use Bulma/Sass build) that no generic CSS or Bulma skill would claim. Clear niche with distinct triggers; minimal conflict risk.