Conciseness

The body is lean and adds judgment the model can't infer (pre-approved seams, tautological-test detection with a concrete `expect(add(a, b)).toBe(a + b)` example, vertical-slices rule), with no padding explaining what TDD is at textbook length. A few sentences could be trimmed — e.g., the explanation of what the `codebase-design` skill is ('是供查阅的 reference，而不是要运行的 session') — so it sits at anchor 4 ('efficient; minor instances of over-explanation') rather than anchor 5's every-token-earns-its-place.

Actionability

Concrete, executable instruction guidance throughout: '先写 failing test，再只写足够让它通过的代码', the pre-test seam-confirmation step with the exact question to ask ('What's the public interface, and which seams should we test?'), and recognizable anti-pattern signatures. It does not reach 5 because key detail is deferred to files that are not in the bundle — mocking rules ('mocking 规则见 mocking.md') and test examples ('示例见 tests.md') point at files that do not exist.

Workflow Clarity

The loop is clearly sequenced with rules that function as checkpoints: red before green, one seam/one test per cycle, refactoring explicitly routed to the review stage, plus an upfront checkpoint (confirm seams with the user before writing any test). This is an instruction skill with no destructive or batch operations, so no validation cap applies; it falls just short of anchor 5 because the red->green cycle is stated as rules rather than an explicit ordered cycle with a verify-the-test-fails step.

Progressive Disclosure

Section structure is clear and the two references ('[tests.md](tests.md)', '[mocking.md](mocking.md)') are one level deep and clearly signaled, but they are dangling — the bundle contains no tests.md or mocking.md, so the promised examples and mocking rules are unreachable. Per the guideline to score against the actual bundle structure, broken references leave this at anchor 3 (structure present but organization undermined) rather than 4, and it cannot take the under-50-lines simple-skill exception because the skill does declare a need for external references.

Specificity

The 'what' is essentially just the domain name '测试驱动开发' (Test-Driven Development) with no concrete actions enumerated (no 'write the failing test first, then implement, then repeat'). This matches anchor 2 ('Names the domain but actions are minimal or generic' — 'Processes PDF files') rather than anchor 3, which requires 1-2 concrete actions; the phrase '用先写测试的方式构建功能或修复缺陷' is a trigger condition, not a listed capability.

Completeness

Both parts are present: a 'what' ('测试驱动开发' with its test-first approach) and an explicit 'when' clause ('适用于...时' with three concrete triggers). It does not reach anchor 5 because the 'what' is a bare domain label rather than an explicit statement of what the skill does, but the 'when' is fully explicit, so it is above anchor 3 (where 'when' is missing or only weakly implied).

Trigger Term Quality

Natural trigger phrases are present and would be said by users: '先写测试' (write tests first), 'red-green-refactor', '构建功能', '修复缺陷', and '集成测试' (integration tests). It misses the most common synonyms a user would naturally say — 'TDD' itself and 'unit tests' — so it falls at anchor 4 ('good keyword coverage; a few natural terms missing') rather than anchor 5's comprehensive synonym coverage.

Distinctiveness Conflict Risk

TDD with triggers like 'red-green-refactor' and 'write tests first' is a clear niche with minimal conflict risk. There is minor overlap with generic testing/write-tests skills (a user asking simply to 'write tests' may not want TDD), matching anchor 4 ('mostly distinct; minor overlap risk with closely related skills') rather than anchor 5.