Conciseness

About 20 lean lines with zero padding: no explaining concepts Claude already knows, no filler sentences. Every directive ("Add one pressure source at a time", "Cap simultaneous committed attackers") earns its place, matching the score-5 lean/efficient anchor.

Actionability

Concrete design checklists ("Define objective, available space, enemy roles, spawn timing, hazards, player resources, exits, failure recovery, and reward") and testable directives ("Create deterministic starts for low resources, each wave, boss phase, victory, and death/retry") give mostly executable guidance. It stops short of 5 because specifics like concrete cap values, a sample encounter fixture, or an example of a "distinct response" per archetype are absent, and "encounter fixtures" from the description are never shown in the body.

Workflow Clarity

A clear compose → fairness-constraints → validate progression with an explicit feedback loop ("Test desktop and mobile at the real camera distance, then adjust composition from observed decisions"). The sequence is implicit in section order rather than explicit steps, and no ordering rationale is stated, so it sits between 4 and 5 — noticeably above 3's implicit-checkpoint level but without the explicit step framing of 5.

Progressive Disclosure

A sub-50-line skill with no bundle files and no content that belongs in separate references; the rubric's simple-skill guideline allows score 5 for well-organized sections, and the three headed sections (Compose / Keep it fair / Validate) are exactly that.

Specificity

"Design, implement, tune, or test Three.js action-game encounters" names four concrete actions over a specific domain, followed by a list of concrete objects ("arena layout, enemy composition, spawn pacing, objectives, boss phases, reward cadence, encounter fixtures, and difficulty validation"). Comprehensive within its niche, matching the score-5 anchor; there are no meaningful coverage gaps that would drop it to 4.

Completeness

Explicitly answers "what" ("Design, implement, tune, or test Three.js action-game encounters") with an explicit "Use for..." trigger clause listing concrete scenarios. This mirrors the score-5 example structure; the "when" is explicit and specific, so 4's 'when could be more explicit' does not apply.

Trigger Term Quality

Good natural-term coverage ("Three.js", "encounter", "boss phases", "spawn pacing", "difficulty validation") that users would plausibly say, but common synonyms like "level design", "waves", "enemy AI", or "balancing" are missing. Fits score 4 (good coverage, a few natural terms missing); it falls short of 5's synonym/extension comprehensiveness but is clearly above the 3 anchor's generic keyword level.

Distinctiveness Conflict Risk

A clear niche (Three.js action-game encounters) with domain-specific trigger terms like "boss phases" and "spawn pacing" that few other skills would claim. Minimal conflict risk; matches the score-5 anchor and shows no overlap broad enough to warrant 4.