Conciseness

The body is ~20 lines with zero padding: no concept explanations, no filler — every line ("Emit only `checks[]`, `metrics[]`, and optional `artifacts[]`", "Keep IDs stable across runs") is actionable guidance Claude doesn't already know. Not below 5 because nothing could be trimmed without losing information.

Actionability

One fully executable command exists ("plugin-eval analyze <path> --metric-pack <manifest.json>") plus concrete field names, but the core step "Create a metric-pack manifest plus a script that prints JSON to stdout" has no manifest example, no output schema, and no script skeleton — the key details live in a reference that cannot be verified. Not a 4 because those missing details are essential to executing the main step, not a minor gap.

Workflow Clarity

The four-step Workflow (clarify → define payload → create manifest+script → run through plugin-eval analyze) is clearly sequenced, and step 4 doubles as a checkpoint. Not a 5 because there is no error-recovery guidance — what to do if the analyze step rejects the pack output is unaddressed.

Progressive Disclosure

Sections (Workflow / Design Rules / Reference) are well-organized for a short skill, but the single reference is a bare path `../../references/metric-pack-manifest.md` that escapes the skill directory two levels up and resolves to no existing file — no references/, scripts/, or assets/ directories exist in the bundle. Not a 4 because a dangling, non-linked reference with an out-of-bundle path is a navigation failure, not a minor organization gap.

Specificity

Phrases like "Design custom metric packs for plugin-eval" and "emit schema-compatible checks and metrics" name several concrete, domain-specific actions in third person. Not a 5 because coverage stops at design/emit — it never mentions creating manifests, running the analysis, or what the emitted checks actually contain, leaving minor gaps.

Completeness

Both parts are present: a clear what ("Design custom metric packs... that emit schema-compatible checks and metrics") and an explicit when ("Use when the user wants their own evaluation criteria or visualizations"). Not a 5 because the when-clause could be more specific — it doesn't tie triggers to plugin-eval or metric packs, and "visualizations" is left unexplained relative to the what.

Trigger Term Quality

Triggers such as "evaluation criteria", "rubrics", and "visualizations" are natural phrases a user would say. Not a 5 because common synonyms and variations ("custom scoring", "evaluation metrics", "local rubric", "plugin-eval extension") are missing, and "visualizations" appears only in the when-clause without support in the what.

Distinctiveness Conflict Risk

"Design custom metric packs for plugin-eval" carves out a clear niche with distinct triggers ("evaluation criteria", "visualizations", plugin-eval itself) that no generic skill would claim. The anchor-4 concern (overlap with closely related skills) doesn't apply since the target tool is named explicitly.