Conciseness

The anti-pattern sections are tight (one-line WHYs, lean BAD/GOOD code) and nothing explains TypeScript basics, but "When to Apply" and "Use When" largely duplicate each other and the frontmatter description, and the Mindset paragraph re-explains design rationale ("a type is a specification the compiler checks") that could be trimmed. Efficient overall with minor instances of over-explanation — the 4 anchor.

Actionability

Three complete, executable BAD/GOOD TypeScript pairs cover the common cases (FetchState discriminated union, Zod `UserSchema.parse(await res.json())`, module encapsulation with `getConnection()`), plus copy-paste commands (`npx tsc --noEmit`, `npm install zod`). Fully executable, copy-paste-ready guidance — the 5 anchor.

Workflow Clarity

The type-first order is implied in Mindset ("Design the types before writing the implementation", "validate once there") and `npx tsc --noEmit` provides a validation checkpoint, but the body never sequences these into an explicit workflow with checkpoints — the actual workflow lives in references/type-first.md. This fits "sequence present but checkpoints missing or implicit" at 3; not 4 because no ordered steps with validation gates appear in the body itself.

Progressive Disclosure

The body is a well-organized overview (mindset, scope, anti-patterns, commands) with a References table mapping each topic to a real one-level-deep file (all four referenced files exist in references/), plus two well-chosen external links. Content is appropriately split between inline overview examples and detail files — the 5 anchor.

Specificity

The description lists multiple concrete actions covering the skill's full surface: "designing types before implementation, making illegal states unrepresentable with discriminated unions, runtime validation with Zod at system boundaries, and module organization (single-function modules, barrel files, encapsulation)". Each action is specific and concrete, matching the comprehensive-coverage anchor rather than the minor-gaps anchor at 4.

Completeness

Both what and when are explicit: the opening sentence enumerates what the skill does, and "Use when starting a new feature by asking what the types should look like first, spotting an interface with too many optional fields..., or deciding how to validate data coming from outside the type system" gives concrete trigger phrases — the exact pattern of the 5 anchor.

Trigger Term Quality

Triggers are natural phrases users would actually say: "starting a new feature", "asking what the types should look like first", "interface with too many optional fields", "an API response, form input, environment variables", plus concrete technical terms (Zod, discriminated unions, barrel files). Scenario-based phrasing covers the variations users would naturally express, fitting the comprehensive anchor.

Distinctiveness Conflict Risk

The type-first design niche has distinct scenario triggers, but the description spans four sub-topics (discriminated unions, Zod validation, module organization) that carry minor overlap risk with closely related skills — e.g., a general validation/schema skill or a general module-organization skill. It fits the "mostly distinct; minor overlap risk with closely related skills" anchor better than the minimal-conflict anchor at 5.