Conciseness

The body is lean overall — it assumes Mermaid syntax knowledge ("Writing Mermaid is not the hard part") and avoids teaching basics — but the Overview's dated measurement narrative ("Measured on 2026-08-30/31 over twelve agent-written diagrams: without the check below, three of three broke...") is several lines of evidence that could be trimmed to one. That matches 'efficient; minor instances of over-explanation that could be trimmed'; score 5 would require every token to earn its place, and the empirical backstory is arguably motivational padding.

Actionability

Fully executable: a copy-paste command ("python3 scripts/validate.py path/to/diagram.md"), exit-code semantics ("Exit 0 means clean; exit 1 prints one line per problem with the line number and the fix"), and concrete diagram-type selection guidance pointing at SPEC.md. Nothing is pseudocode or vague, matching the 'fully executable; copy-paste ready' anchor.

Workflow Clarity

The five steps are clearly sequenced with an explicit validation checkpoint (step 4) and a feedback loop (step 5: "Repair anything it reports and run it again. Repeat until it is clean. Only then present the diagram"), reinforced by rules 1 and 2. This matches the anchor 5 example of validate → fix → re-validate → only then proceed.

Progressive Disclosure

SKILL.md is a concise overview that keeps only the summary of what the check covers inlined, while the hazard details live one level deep in references/SPEC.md (verified real, 94 lines, no further nested skill references) and the script is linked from both step 4 and the Resources section. Both references are clearly signaled and easy to navigate, matching the 'clear overview with well-signaled one-level-deep references' anchor.

Specificity

"Draw and edit Mermaid diagrams in Markdown" names the domain and two concrete actions (draw, edit) but stops there — it does not mention the validate/repair workflow or diagram-type selection that the skill actually performs. This matches the 'names domain and 1-2 concrete actions, but not comprehensive' anchor; score 4 would require several specific actions listed.

Completeness

It explicitly answers what ("Draw and edit Mermaid diagrams in Markdown") and when ("Use when the user wants to visualize processes, flows or sequences, or asks for a diagram"), plus a concrete load directive ("Load it before writing any Mermaid block"). Both halves are explicit with concrete trigger phrases, matching the anchor 5 example.

Trigger Term Quality

Natural user phrasings are present — "asks for a diagram", "visualize processes, flows or sequences", "Mermaid block" — giving good keyword coverage. A few common natural terms are missing ("flowchart", "sequence diagram", "architecture/ER diagram", ".mmd"), so it falls just short of the comprehensive-synonyms anchor 5.

Distinctiveness Conflict Risk

"Mermaid" is a clear niche with distinct, unambiguous triggers; no generic wording that would cause another skill to fire instead. Matches the 'clear niche with distinct triggers; minimal conflict risk' anchor.