Conciseness

The body is dense with non-obvious, version-specific guidance ("The composer's buffers are not multisampled; `antialias: true` on the renderer does not reach them", "bloom() returns only the glow, so add it to the scene color") and never pads with concepts Claude already knows. Minor trimmable redundancy remains: import blocks for EffectComposer/RenderPass/OutputPass are repeated across ~10 examples, and pass-ordering facts (FXAA after OutputPass, SMAA before) appear in Pass Order, Custom Passes, and Common Mistakes — deliberate reinforcement, but still repeated tokens. Not 5 because of that repetition; not 3 because nearly every sentence carries information Claude would otherwise get wrong (r175 signature changes, deprecated Clock/PostProcessing renames).

Actionability

Every section is copy-paste-ready executable code with concrete parameter values and inline explanations ("focus: 10.0, // view-space depth that stays sharp", "new HalftonePass({ shape: 1, radius: 4, ... })"), spanning the common cases: bloom, selective bloom, DOF, SSAO, outline, film/glitch/halftone/vignette, pixelation, custom ShaderPass, renderer setEffects, and the full WebGPU/TSL node pipeline. The Common Mistakes section pairs wrong code with the exact corrected line ("new FilmPass(0.35, 0.5, 648, false) → new FilmPass(0.35, false)"). Later snippets reuse `renderer`/`scene`/`camera` from the Quick Start, which is conventional and does not undermine executability.

Workflow Clarity

The core multi-step process — pass chain construction — is explicitly sequenced with rules: "Build chains in this order: `RenderPass` → linear-space effects (bloom, depth of field, SSAO, outline, ...) → `SMAAPass` ... → `OutputPass` → `FXAAPass` only when FXAA is used", plus per-pass ordering constraints ("SSAOPass darkens the image ... so a `RenderPass` must come before it"). Error-recovery feedback is provided by the Common Mistakes section (26 wrong→right pairs) and debug aids ("ssaoPass.output = SSAOPass.OUTPUT.SSAO (or Blur, Depth, Normal)"). Not 4 because the ordering rules and recovery guidance are explicit rather than merely present with gaps.

Progressive Disclosure

The body is well-sectioned (Quick Start, Pass Order, per-effect sections, WebGPU and TSL, Common Mistakes, See Also) and the See Also section cross-navigates to sibling skills ("threejs-fundamentals — renderer creation, sizing, color spaces"). However, the entire ~500-line skill lives inline in SKILL.md with no bundle files at all; the WebGPU/TSL pipeline (a distinct renderer path) and the 26-entry Common Mistakes list are natural candidates for a references/ file to keep the main body lean. Not 3 because the structure is clean and navigable with no buried references; not 5 because content that could be split out is inlined in a single monolithic file.

Specificity

Multiple concrete capabilities are listed comprehensively across all three supported paths: "composer pass chains, built-in renderer effects, and the WebGPU/TSL node pipeline — bloom, depth of field, ambient occlusion, custom screen effects". Each named capability is a real, distinct feature of the skill. Not 4 because coverage is comprehensive rather than having minor gaps.

Completeness

Both halves are explicit: the 'what' is the concrete capability list above, and the 'when' is a dedicated clause — "Use when adding visual effects, color grading, blur, glow, or screen-space shaders, on WebGL or with WebGPU and TSL." Not 4 because the trigger conditions are explicit and concrete rather than improvable-but-present.

Trigger Term Quality

Natural user phrasings are thoroughly covered: "bloom", "depth of field", "ambient occlusion", "visual effects", "color grading", "blur", "glow", "screen-space shaders", "post-processing", plus renderer terms "WebGL", "WebGPU and TSL" — these are exactly the words a developer would say when they need this skill. Not 4 because no common variation in this domain is obviously missing.

Distinctiveness Conflict Risk

The niche is clear — Three.js post-processing specifically, including the WebGPU/TSL distinction — and would rarely trigger the wrong generic skill. Minor overlap risk remains with the closely related sibling skill `threejs-shaders` (referenced in the body's See Also): the trigger "custom screen effects" / "screen-space shaders" would also fire for general shader-authoring requests that belong to that skill. Not 5 because of that one closely-related overlap; not 3 because the scope is far more specific than a broad domain claim.