Conciseness

The body never explains concepts Claude already knows (no Docker/compose primer); every step is a command, a file snippet, or a direct instruction like "Use the Edit tool — do not rewrite the entire file". Lean and efficient with every token earning its place matches anchor 5; it is not 4 because there is no over-explanation to trim.

Actionability

Fully executable throughout: an inline context-detection bash command, conditional cp commands per mode, a concrete dockerfile RUN apt-get block with placeholders, and copy-paste rebuild commands per mode. Matches the copy-paste-ready anchor; it is not 4 because the guidance covers the common cases (both dev and deploy modes, missing/present files, arguments present/absent).

Workflow Clarity

A clear five-step sequence with mode branching, an explicit UNKNOWN_MODE fallback ("ask the user which directory their docker-compose.yml lives in"), and protective checkpoints ("Do NOT overwrite existing files", "Do NOT run it automatically"). Missing an explicit validation/feedback loop after editing Dockerfile.user (nothing verifies the edit or that the install succeeds), so it matches anchor 4 with minor validation gaps; it is not 5 because there is no validate-and-retry step, and not 3 because state checks in Step 2 and the conditional guards act as real checkpoints for the risky parts (overwriting files).

Progressive Disclosure

No bundle files exist, and the single-file structure with labeled Step sections and a Summary is appropriately contained for this scope. Good structure with minor organization gaps (duplicated DEV_MODE/DEPLOY_MODE parallel blocks inflate the body to ~93 lines) matches anchor 4; it is not 5 because the under-50-line simple-skill exception does not apply and the duplicated per-mode blocks could be tightened.

Specificity

"Interactively sets up Dockerfile.user and docker-compose.override.yml so users can add personal tools to their Docker environment without affecting maintainer files or committing user-specific config to git" names two concrete files, the concrete action, and the outcome with side-effect boundaries. This matches the anchor for multiple specific concrete actions with comprehensive coverage; it is not 4 because there are no minor gaps in what the skill does.

Completeness

Explicit "Use when:", "Triggers:", and "Does:" clauses clearly answer both what the skill does and when to use it, with concrete trigger phrases. This is the anchor case for answering both what AND when explicitly; it is not 4 because the when is not merely present but enumerated.

Trigger Term Quality

The explicit trigger list ('extend docker', 'add tools to docker', 'customize docker', 'add my tools to the container', 'personalize docker setup', 'docker user setup', 'install tools in docker') covers natural phrasing variants users would actually say. Comprehensive synonym coverage matches the top anchor; it is not 4 because both imperative and descriptive variants are present.

Distinctiveness Conflict Risk

The niche (gitignored personal Docker override files) is distinct, but generic triggers like 'customize docker' and 'docker user setup' could overlap with general Docker/compose setup skills. Mostly distinct with minor overlap risk matches anchor 4; it is not 5 because those generic phrases leave non-minimal conflict surface with sibling Docker skills, and not 3 because the file-level triggers (Dockerfile.user, docker-compose.override.yml) anchor it firmly.