Conciseness

The 49-line body is dense, directive, and free of padding — it never explains concepts Claude already knows (no 'what TDD is', no library tutorials) and each numbered step states a rule or command. It matches the anchor-5 'lean and efficient; every token earns its place' profile; anchor 4 would require noticeable over-explanation that is absent here.

Actionability

Concrete, executable guidance dominates: copy-paste commands ('npx ai-devkit@latest lint --feature <name>'), config resolution ('.ai-devkit.json' 'paths.docs', falling back to 'docs/ai'), explicit task statuses, and per-task doc update contents. It misses anchor 5 because a few items remain underspecified — e.g., step 11 says 'Generate a markdown tracking snippet after each status change' without showing the snippet's shape, and the phase-tracing event format is left entirely to the parent dev-lifecycle skill.

Workflow Clarity

Both phase sections have clearly sequenced numbered steps with explicit validation checkpoints: lint before work, TDD's failing-test-first loop, the 'verify' skill before completion claims, per-task doc lockstep updates, 'After each section, ask if new tasks were discovered', and error-recovery routing ('If major deviations exist, return to dev-design if design is wrong or Execute Plan if implementation is wrong'). This matches the anchor-5 pattern of clear sequence, explicit validation, and feedback loops.

Progressive Disclosure

The skill is under 50 lines with no bundle files (references/, scripts/, assets/ are absent) and no need for external references, and its sections (Phase Contract, Execute Plan, Check Implementation) are well-organized. Per the rubric's simple-skill guideline, well-organized sections alone merit 5; the cross-references it does make (tdd, verify, dev-planning, dev-testing, dev-review) are one level deep and clearly signaled.

Specificity

The description lists several concrete actions — 'executing feature plans', 'checking implementation against design', 'update implementation docs', and 'run dev-lifecycle phases 5 and 7' — rather than vague capability claims. It falls short of anchor 5 because coverage is narrowly scoped to the two lifecycle phases, while it exceeds anchor 3, which expects only 1-2 concrete actions.

Completeness

It explicitly answers both questions: the 'what' ('Implementation phase guidance for executing feature plans and checking implementation against design') and a concrete 'when' with four explicit trigger phrases in the 'Use when...' clause. This matches the anchor-5 example structure of a clear capability statement followed by concrete 'Use when' triggers.

Trigger Term Quality

The 'Use when' clause provides good natural trigger phrases — 'implement planned tasks', 'update implementation docs', 'verify code matches design', 'run dev-lifecycle phases 5 and 7' — that users of this toolkit would plausibly say. It misses anchor 5 because common synonyms like 'execute the plan', 'code the tasks', or 'implementation review' are absent, and the phase-number jargon is system-specific.

Distinctiveness Conflict Risk

The 'AI DevKit' brand prefix and phase-specific triggers ('dev-lifecycle phases 5 and 7', 'checking implementation against design') give it a clear niche within its skill family with minimal conflict risk. It is not anchor 5 because 'implement planned tasks' and 'verify code matches design' could mildly overlap with sibling skills like dev-planning or a general code-review skill.