Conciseness

The body is a single sentence with zero padding, no over-explanation of known concepts, and nothing to trim — maximally token-efficient. The vacuousness of the body is penalized under actionability and workflow_clarity, not here, since this dimension measures verbose vs. lean and the body sits at the extreme lean end.

Actionability

The body provides no concrete TDD guidance whatsoever — no code, no commands, no steps for the red-green-refactor process the description promises. Worse, it instructs the agent to 'Do not run any commands, read any files, or change anything' and 'Reply with `DONE`', which actively forbids action rather than guiding it. Not 2: there are not even high-level hints toward executing the skill's purpose.

Workflow Clarity

TDD is inherently multi-step (failing test, run, minimal code, refactor), yet the body contains no sequence, no steps, and no validation checkpoints — the 'what' exists only in the frontmatter description. Not 2: even a rough sequence with gaps would score higher, but here the workflow is entirely absent from the body.

Progressive Disclosure

The bundle contains a substantive reference file (references/writing-good-tests.md, covering test-writing principles with examples), but the body never mentions or links it — the reference is completely buried and undiscoverable from SKILL.md. Not 1: the body is not a monolithic wall of text and references are not nested; not 3+: no reference is signaled at all, so navigation from the overview to the detail content is impossible.

Specificity

The description enumerates the full concrete cycle — 'write one failing test, run it and watch it fail, write the minimal code to pass, then refactor with the tests green' — four specific actions with comprehensive coverage of the test-first workflow. Not 4: there are no coverage gaps in the action list; not below: every action is concrete, not generic.

Completeness

Explicitly answers both parts: the 'what' ('Implements a feature or bug fix test-first...') and the 'when' ('Use when a change alters code behavior: a new feature, a bug fix, or a behavior change...'). Not 4: the 'when' clause is not merely present but enumerates concrete trigger phrases.

Trigger Term Quality

Natural user phrasings are present — 'a new feature, a bug fix, or a behavior change' — which map well to how users actually ask. Not 5: common variations like 'write tests', 'unit test', 'regression', or 'TDD' itself are missing; not 3: the terms present are natural and relevant, not generic.

Distinctiveness Conflict Risk

The TDD niche ('test-first' with an explicit red-green-refactor cycle) is clearly distinguishable from other skills' actions. Not 5: the trigger 'a new feature, a bug fix, or a behavior change' fires on virtually any code change, creating overlap risk with general implementation and delivery-flow skills ('whether the request comes alone or through delivery-flow' explicitly spans another skill's domain); not 3: the action itself is a distinct, well-defined methodology.