Conciseness

The body is lean and imperative ("Write the test first. Watch it fail. Write the minimal code to pass. Refactor with the tests green.") with zero padding and no re-explanation of TDD concepts Claude already knows. Every token earns its place, matching the level-5 anchor exactly.

Actionability

The guidance is concrete and executable — "Run the project's test command", "The test must fail because the behavior is missing, not because of a typo or a missing import", "If it passes, it tests nothing new: change the test" — with validation criteria for each step. It falls short of level 5 only because no example command or concrete test snippet is shown (justifiably project-dependent, but still a minor gap), matching the level-4 anchor; per the scoring notes, absence of code in an instruction-only skill is not penalized when guidance is actionable.

Workflow Clarity

The five-step cycle is clearly sequenced with explicit validation checkpoints ("Watch it fail" with failure-mode diagnosis, "Watch it pass. Run the full suite. Every test passes, with no errors or warnings", "Run the suite again" after refactor), an error-recovery feedback loop (test passes early → change the test), and a done-checklist ("Before you say it is done"). This matches the level-5 anchor: clear sequence, explicit validation, feedback loops, and a checklist.

Progressive Disclosure

The body is under 50 lines, well-organized into sections (The cycle, Rules, Before you say it is done), and includes one clearly-signaled, one-level-deep reference — "read [references/writing-good-tests.md](references/writing-good-tests.md)" — which exists as a real file containing no nested references. Per the judging guidelines, a short skill with no need for external references scores 5 with just well-organized sections, and the single well-signaled reference reinforces this.

Specificity

The description lists the complete concrete action cycle — "write one failing test, run it and watch it fail, write the minimal code to pass, then refactor with the tests green" — giving comprehensive coverage of the skill's behavior. It matches the level-5 anchor (multiple specific concrete actions, comprehensive) rather than level 4, which expects minor coverage gaps.

Completeness

It explicitly answers both questions: the "what" is the full test-first cycle and the "when" is "Use when a change alters code behavior: a new feature, a bug fix, or a behavior change". This matches the level-5 anchor (clear, explicit what AND when with concrete trigger phrases); level 4 would require the "when" to be less explicit or specific.

Trigger Term Quality

Natural user phrases like "a new feature", "a bug fix", and "a behavior change" are present and would be said when this skill is needed, but common synonyms such as "TDD", "red-green", or "unit test" are missing. Good keyword coverage with a few natural terms absent fits the level-4 anchor; level 5 requires synonyms and variations, and level 3 would mean the core phrases users actually say are missing, which is not the case.

Distinctiveness Conflict Risk

Test-driven development is a distinct methodology niche, so the skill is mostly distinguishable, but the trigger claims essentially any code-behavior change ("whether the request comes alone or through delivery-flow"), creating minor overlap risk with closely related workflow and delivery skills. This fits level 4 (mostly distinct, minor overlap risk) rather than level 5's minimal-conflict standard.