Conciseness

The body is mostly efficient and dense with actionable material, but includes content Claude already knows: the 15-command CLI cheat sheet ('docker run -d --name web', 'docker logs -f', 'docker system prune -f'), the prerequisites section (usermod/docker group), and basic explanations like 'Docker evaluates cache from top to bottom'. This matches 'Mostly efficient but includes some unnecessary explanation or could be tightened' rather than the 2 anchor, since most sections (BuildKit cache mounts, distroless tradeoffs, opcache settings) carry genuinely non-obvious value.

Actionability

Nearly everything is copy-paste-ready executable code: three complete production Dockerfiles (Node/Next.js standalone, PHP-FPM/WordPress, Python venv multi-stage), full .dockerignore, Compose v2 YAML, BuildKit secret commands, and a verification script set. This matches 'Fully executable; copy-paste ready code or commands; specific examples cover the common cases'; the only blemish (the 'FROM base-runtime AS builder' placeholder) is in a section explicitly labeled a template.

Workflow Clarity

The nine steps form a clear, logical build sequence (base image → context hygiene → Dockerfile → stacks → security → volumes/networks → Compose → dev/prod split → debugging), capped by an explicit Verification section with concrete commands (build, 'docker run --rm test-image:local id', CVE scan, 'docker compose config', 'docker compose ps') and a dedicated debugging section for error recovery. This matches 'Clear sequence with explicit validation steps; feedback loops for error recovery; checklists for complex processes'; a 4 would require missing checkpoints, which are present.

Progressive Disclosure

The bundle is real and correctly wired — 'references/compose-patterns.md' exists, is referenced exactly once in a clearly signaled 'Deep Dive Reference' section, and is one level deep, matching 'Good structure; most content is appropriately placed; references mostly clear'. It falls short of the 5 anchor because substantial content that could live in the reference (three full stack Dockerfiles and a complete .dockerignore) is inlined in SKILL.md, keeping the body at ~650 lines.

Specificity

The description lists many concrete actions — 'design multi-stage Dockerfiles, configure Docker Compose v2 stacks, optimize image layers and caching, manage networks, volumes, and secrets, and harden container security' — covering the domain comprehensively across three named stacks. It matches the anchor 'Lists multiple specific concrete actions; comprehensive coverage' and falls short of nothing below it; no vagueness is present.

Completeness

The 'what' is clear and detailed, but there is no 'Use when...' clause or equivalent explicit trigger guidance anywhere in the description — the user must infer applicability. Per the rubric guidelines, a missing 'Use when' clause caps completeness at 3, which is exactly the anchor 'Has a clear what but when is missing or only weakly implied'; a 4 would require an explicit, if imperfect, 'when' statement.

Trigger Term Quality

Natural terms users would say are present ('Dockerfile', 'Docker Compose', 'containerize', 'image', 'caching', 'volumes', 'secrets'), giving good keyword coverage. It falls short of the 5 anchor because common synonyms and file extensions are missing (e.g., 'dockerize', 'build images', 'docker-compose.yml', '.dockerignore'), while it clearly exceeds the 3 anchor's 'missing common variations'.

Distinctiveness Conflict Risk

Docker tooling ('Dockerfiles', 'Docker Compose v2') gives a clear niche with mostly distinct triggers, but 'manage networks, volumes, and secrets' and the three-stack breadth create minor overlap risk with adjacent skills (e.g., a Kubernetes/orchestration skill, or stack-specific WordPress or Node.js deployment skills). This matches 'Mostly distinct; minor overlap risk with closely related skills' rather than the 5 anchor's minimal-conflict profile.