Conciseness

The body is lean and assumes competence throughout: no concept explanations, no library tutorials, and terse declarative rules like "Colocation is the default" and "Prove the smallest honest surface". Every token instructs, matching the 5 anchor rather than the 4 anchor, which still expects minor over-explanation to trim.

Actionability

Concrete, runnable guidance is present — exact commands ("pnpm --filter platejs build", "node tooling/scripts/check-plate-feature.mjs <plan>"), exact paths, and named APIs ("definePlugin", "toReactPlugin") — but the mechanics of authoring are deferred to reference files and no inline code examples are given. This sits between the 4 anchor (mostly executable, minor gaps) and the 5 anchor (copy-paste ready coverage of common cases), landing at 4.

Workflow Clarity

The 8-step Workflow is clearly sequenced with explicit validation checkpoints (step 7 lists typecheck, behavior tests, and a build with its failure rationale "TS4094 errors the typecheck skips") plus a step-8 audit checklist. It stops short of the 5 anchor because there is no explicit fix-and-re-validate feedback loop; it is above the 3 anchor since checkpoints are explicit rather than implicit.

Progressive Disclosure

Signaling is excellent ("Read this reference when…", one-level-deep references such as package-host.md and feature/manifest.md), but scored against the actual bundle: the required reads ./rules/creation-flow.md, ./rules/typing.md, and ./rules/capabilities.md do not exist, and ../verify/references/testing.md points outside the skill. Broken required-read navigation exceeds the 4 anchor's "minor organization gaps" while the clear structure and surfaced references keep it above the cluttered/buried pattern of lower anchors.

Specificity

The description lists multiple concrete actions and artifacts: "Builds Plate plugins and entrypoints", "adding or changing a plugin's stage fields or options, such as read middleware, contributions, transfer vetoes or landing policy", and "delivers a feature across its package, UI, docs and release". Coverage is comprehensive within its niche, so it matches the 5 anchor rather than the 4 anchor, which reserves room for gaps.

Completeness

It explicitly answers "what" ("Builds Plate plugins and entrypoints with semantic ownership, inference, scoped capabilities and package proof") and "when" through three concrete trigger clauses ("Use before adding or changing…", "Load it before any edit to a Base plugin file…", "Use it also when a change touches…"). Both halves are explicit with concrete trigger phrases, matching the 5 anchor rather than the 4 anchor's softer "when".

Trigger Term Quality

Natural trigger vocabulary is thorough and includes path-level triggers users would actually encounter: "Base plugin file under packages/platejs/src", "packages/platejs/src/features/*/lib/Base*Plugin.ts", "stage fields", "encode or decode mapping", "Plite, Plate, the registry and docs". No natural synonym or file-pattern variation is missing, which fits the 5 anchor rather than the 4 anchor's "a few natural terms missing".

Distinctiveness Conflict Risk

The niche is unambiguous: Plate/Plite plugin authoring scoped by exact file globs and plugin-specific terms ("stage fields", "transfer vetoes", "preserve claims"), so it is unlikely to fire for unrelated skills. This matches the 5 anchor's "clear niche with distinct triggers; minimal conflict risk" rather than the 4 anchor, which still allows overlap with closely related skills.