Conciseness

The body is lean and imperative throughout — "One agent, one pass, no subagents... Nothing else." and "Diagrams supplement the plan — they never editorialize it." — with no explanations of concepts Claude already knows. Every section carries a rule or a copy-paste block; nothing is padded.

Actionability

Fully executable: a copy-paste-ready store-resolver bash block, exact output-path rules ('strip the trailing .md, append .diagrams.md'), a plan-content-to-diagram-type mapping table, and concrete constraints ('~40 nodes max', quoting example 'A["label (with) specials"]'). Specific guidance covers the common cases.

Workflow Clarity

Clear sequence (resolve store → output path → content policy → diagram selection → HTML alternative → report) with a fallback for blank input and an explicit, justified overwrite decision ('derived artifact; the plan is the source of truth'). Minor gap: it instructs that 'Mermaid syntax must be valid' but includes no post-generation validation check, fitting 'clear sequence with most checkpoints; minor validation gaps'. The destructive-operation cap does not apply since the overwrite behavior is an explicit, reasoned decision on a derived file.

Progressive Disclosure

No bundle files exist, and the single-file body is cleanly sectioned with no content inlined that clearly belongs elsewhere. Minor gap: the 13-line canonical store resolver (marked 'keep byte-identical across skills') could live in a shared script file, and the body is slightly over the under-50-lines simple-skill threshold — 'good structure; minor organization gaps' rather than the fully optimal anchor.

Specificity

"Generate a mermaid-only visual supplement for a plan artifact - the data-model, architecture, and flow diagrams" names the domain and several concrete deliverables (diagram categories), with only minor coverage gaps (a single generate verb rather than multiple enumerated actions). It exceeds anchor 3 (more than 1-2 concrete actions) but is less comprehensive than anchor 5.

Completeness

Explicitly answers both: what ("Generate a mermaid-only visual supplement for a plan artifact - the data-model, architecture, and flow diagrams") and when ("Use when the user wants to 'diagram this plan', ... or invokes $prp-diagram") with concrete trigger phrases.

Trigger Term Quality

Four natural, synonym-rich quoted phrases — "diagram this plan", "visualize the plan", "draw the plan's architecture", "make diagrams for this plan" — plus the explicit "$prp-diagram" invocation, matching the comprehensive-synonyms anchor. A user would naturally say these exact phrases; no meaningful terms are missing.

Distinctiveness Conflict Risk

Clear niche (mermaid-only diagrams for plan artifacts) with distinct triggers, but minor overlap risk with general diagramming or visualization skills that could also fire on 'draw the architecture'. Anchored at 'mostly distinct; minor overlap risk with closely related skills'.