Conciseness

The body is lean and directive with no filler, no library tours, and no basic-concept padding; sections like 'Rules of the loop' are one line each. A few sentences re-explain concepts Claude already knows (e.g., defining 'seam', explaining what a tautological test is at length with examples like `expect(add(a, b)).toBe(a + b)`), which keeps it just below the 'every token earns its place' anchor.

Actionability

For an instruction-only skill the guidance is concrete: an exact question to ask ('What's the public interface, and which seams should we test?'), explicit rules ('Write the failing test first, then only enough code to pass it', 'One seam, one test, one minimal implementation per cycle'), and a named tool invocation ('call the Skill tool with "codebase-design"'). It misses anchor 5 because the concrete good-test and mocking examples are delegated to files that don't exist in the bundle, leaving minor gaps in executable specificity.

Workflow Clarity

The loop is clearly sequenced — agree seams with the user, red (failing test) before green (minimal implementation), one slice at a time — and includes an explicit checkpoint ('write down the seams under test and confirm them with the user. No test is written at an unconfirmed seam'). It stops short of anchor 5: there is no explicit verify-the-test-fails step or error-recovery loop, and refactoring is delegated out without saying when review happens.

Progressive Disclosure

Sections are well organized and the references are clearly signaled ('See [tests.md](tests.md)... [mocking.md](mocking.md)'), but the bundle contains no such files — no references/, scripts/, or assets/ directories exist — so both links are dangling and navigation breaks. Scored against the actual (empty) bundle structure, this is 'structure present but references not resolvable', between the broken/minimal-structure anchors and the good-structure anchor 4.

Specificity

The description names the domain ('Test-driven development') and conveys the concrete activity ('build features or fix bugs test-first'), but lists no specific capabilities of the skill itself (e.g., test design guidance, seam selection, anti-patterns), so coverage is not comprehensive. It sits between anchor 2 (domain only, generic actions) and anchor 4 (several specific actions) — it is more than a bare domain label but lacks the skill-side action list of anchor 4.

Completeness

Both parts exist: 'what' ('Test-driven development') and an explicit 'when' clause with multiple concrete triggers. It falls short of anchor 5 only because the 'what' is a bare domain name without stating what the skill actually provides (test-quality rules, seam agreement, anti-patterns), leaving the capability side thinner than the trigger side.

Trigger Term Quality

Natural trigger phrases are present: 'build features', 'fix bugs test-first', 'red-green-refactor', 'integration tests' — terms a user would plausibly say. A few common variations are missing (e.g., 'TDD', 'write tests first', 'unit tests'), matching the 'good keyword coverage; a few natural terms missing' anchor rather than the comprehensive synonym/extension coverage of anchor 5.

Distinctiveness Conflict Risk

TDD is a clear niche with distinct triggers ('test-first', 'red-green-refactor'), so it is mostly distinguishable from general coding or code-review skills. Minor overlap risk remains: 'wants integration tests' alone could pull this skill in when the user just wants tests written, not a TDD loop — matching 'mostly distinct; minor overlap risk' rather than the minimal-conflict anchor 5.