Conciseness

The body is almost entirely code with inline parameter comments and no concept explanations Claude already knows, which is efficient; but it 'could be tightened' per the 3 anchor — the EffectComposer setup, imports, and resize handling are duplicated three times (Quick Start, EffectComposer Setup, Handle Resize), and version-sensitive content like 'WebGPU Post-Processing (Three.js r150+)' sits outside any deprecated/version-note section. It is not a 2 because there is no conceptual padding or fluffy prose, and not a 4 because the repeated setup blocks are a substantial share of the file rather than minor trimmings.

Actionability

Nearly every section is copy-paste-ready code with concrete parameter values and comments ('1.5, // strength', 'focus: 10.0'), plus runtime adjustment snippets, matching the 4 anchor ('mostly executable guidance; concrete code with minor gaps'). Not a 5 because of small gaps: the WebGPU block is not executable as written (it imports 'postProcessing' as a named import and then redeclares 'const postProcessing', and 'pass, bloom, dof' are not exported from that module path), and the FilmPass constructor uses the legacy 4-argument signature that newer three.js versions replaced.

Workflow Clarity

Quick Start gives an unambiguous start-to-finish sequence (create composer -> add RenderPass -> add effect pass -> call composer.render() instead of renderer.render()), and 'Combining Multiple Effects' numbers the pass ordering with explicit ordering rules ('Anti-aliasing (always last before output)'), matching the 4 anchor. Not a 5 because there are no validation or troubleshooting checkpoints (e.g., verifying the composer renders, common black-screen causes), though this reference-style skill carries no destructive/batch risk that would cap the score.

Progressive Disclosure

There are no bundle files (no references/, scripts/, assets/), and the ~600-line body inlines fifteen-plus per-effect snippets and custom shader examples that clearly belong in separate reference files, matching the 3 anchor ('some structure... content that should be separate is inline'). Structure itself is good — clear section headers, a Quick Start up front, and a See Also list — so it is above the 2 anchor (which requires minimal structure), but the entire catalog sits in SKILL.md rather than being split behind one-level-deep references, so it does not reach 4.

Specificity

Names the domain ("Three.js post-processing") and several concrete capabilities ("EffectComposer, bloom, DOF, screen effects"), which matches the 'several specific actions; minor gaps' anchor rather than the vague or minimal anchors. It falls short of the 5 anchor because the items are component names rather than concrete actions and 'screen effects' is generic, while it clearly exceeds the 3 anchor ('names domain and 1-2 concrete actions, but not comprehensive') by listing four specific technologies.

Completeness

Explicitly answers both questions: the what is "Three.js post-processing - EffectComposer, bloom, DOF, screen effects" and the when is "Use when adding visual effects, color grading, blur, glow, or creating custom screen-space shaders" with five concrete trigger phrases, exactly matching the 5 anchor. The 4 anchor ('when could be more explicit or specific') does not apply since the trigger list is already explicit and specific; the 3 anchor ('when is missing or only weakly implied') is clearly inapplicable.

Trigger Term Quality

The when-clause uses natural user phrasing — "adding visual effects", "color grading", "blur", "glow", "creating custom screen-space shaders" — giving good keyword coverage as in the 4 anchor ('good keyword coverage; a few natural terms missing'). Not a 5 because common variations a user would actually say are missing from the trigger clause (e.g., bloom, anti-aliasing/FXAA, post-processing itself as a trigger phrase, or a 'when the user mentions X' form).

Distinctiveness Conflict Risk

Pinning to "Three.js" plus "post-processing" and "screen-space shaders" gives it a clear niche with mostly distinct triggers, matching the 4 anchor ('mostly distinct; minor overlap risk'). Not a 5 because "adding visual effects" is broad enough to also match non-post-processing three.js requests (particles, materials, lighting), and "creating custom screen-space shaders" overlaps with a general shader-development skill like the 'threejs-shaders' skill it cross-references.