Conciseness

The body is dominated by tight, executable Swift snippets with one-or-two-line framing (e.g., "Use `.applyImpulse` for jumps and projectile launches"), and it avoids explaining concepts Claude already knows like what a game engine is. Not 5 because a ~495-line body includes trimmable material — the 11-item Contents TOC duplicates the heading structure, and sections like Camera zoom/HUD and SpriteView Options carry prose that could be condensed or pushed to the reference file. Not 3 because the padding is minor, not 'several unnecessary explanations'.

Actionability

Nearly every section leads with copy-paste-ready, syntactically complete Swift: the GameScene subclass, contact-delegate extension with bit-mask matching, one-shot emitter with lifetime-based removal, and the SwiftUI `@State` scene pattern. Concrete pitfalls are shown as DON'T/DO pairs (scene recreation, contactTestBitMask, offscreen node removal). This matches the anchor-5 'fully executable, copy-paste ready, common cases covered'.

Workflow Clarity

The body sequences topics in build order (scene setup → nodes → actions → physics → touch → camera → SwiftUI), lists the frame-cycle order explicitly, and closes with a 17-item Review Checklist that functions as a validation checkpoint; the Common Mistakes section supplies corrective guidance for each failure mode. Not 5 because there are no explicit feedback loops (build → run → verify output) for the setup/present-scene workflow, though nothing here is destructive or batch-operated so the hard cap does not apply.

Progressive Disclosure

Core usage lives in SKILL.md while advanced material (tile maps, texture atlases, shaders, scene transitions, audio, SceneKit embedding) is correctly split into a real, verified one-level-deep reference that is clearly signaled with its contents enumerated in the References section. Not 5 because the main file runs ~495 lines — borderline monolithic for an 'overview' — and secondary topics like Camera details and Particle Effects could arguably join the reference file; not 3 because the split that exists is well-signaled and easy to navigate via the TOC.

Specificity

The description enumerates concrete, distinct capabilities: "creating game scenes with SKScene and SKView", "animating with SKAction sequences", "simulating physics with SKPhysicsBody and contact detection", "creating particle effects with SKEmitterNode", "building tile maps", "using SKCameraNode", and "integrating SpriteKit scenes in SwiftUI with SpriteView" — comprehensive coverage of the framework's surface. Not level 4 because there are no noticeable gaps; every major SpriteKit subsystem is explicitly named as an action.

Completeness

Explicitly answers both questions: the "what" is "Build 2D games and animations using SpriteKit" and the "when" is a concrete "Use when" clause listing seven specific triggering scenarios. Matches the anchor-5 example structure (what + when with concrete trigger phrases) exactly; level 4 would require a vaguer or less enumerated 'when'.

Trigger Term Quality

Good natural keyword coverage: "2D games", "animations", "sprites", "physics", "contact detection", "particle effects", "tile maps", "SwiftUI" are phrases users would naturally say, alongside the distinctive SK class names. Not 5 because common synonyms and extensions are missing — e.g., "iOS game development", "game engine", or the `.sks` particle file extension; not 3 because the terms present are varied and natural rather than minimally generic.

Distinctiveness Conflict Risk

"SpriteKit" plus class names like SKSpriteNode, SKEmitterNode, and SpriteView define a clear niche with essentially no overlap risk against non-Apple or non-game skills. The triggers are framework-specific, matching the anchor-5 'clear niche with distinct triggers; minimal conflict risk'.