Conciseness

The ~45-line body is lean: no 'what is WebGL' padding, no library tutorials, and the one conceptual section ('Why this is a powered artifact') conveys platform-specific OpenDesign sandbox facts Claude cannot know, so every token earns its place. It is not 4 because there is no section that reads as trimmable over-explanation.

Actionability

Concrete, executable specifics are present — 'alpha:false, DPR clamped to 2', 'getShaderInfoLog', the four named techniques, 'Headline ≤ 14ch', and a described canvas/draw-loop/resize structure. It is not 5 because the body contains no code snippet and its working reference is external; it is not 3 because the guidance given is specific and directly executable for an instruction-only skill, with only a minor gap left to the (missing) reference file.

Workflow Clarity

Steps 0–4 are clearly sequenced and end in an explicit P0 self-review checklist (60fps, clean getError(), resize crispness, contrast, graceful degradation), plus build-time error logging via getShaderInfoLog. It is not 5 because there is no explicit 'if a checklist item fails, fix and re-verify' recovery loop; it is not 3 because validation checkpoints are explicit, not merely implied.

Progressive Disclosure

Sections are well organized and the reference is loudly signaled ('READ FIRST', a resource map), but the bundle does not actually contain example.html — the single referenced file is missing, so the promised one-level-deep detail cannot be loaded. Per the guideline to score against the actual bundle structure, this broken reference leaves the disclosure structure not better than 'some structure' despite the clean sectioning.

Specificity

Multiple concrete capabilities are enumerated — 'animated shaders, 3D scenes, generative visuals, particle fields — rendered live on the GPU with a typographic overlay' — plus the concrete output form 'a single self-contained index.html'. This matches the comprehensive multi-action anchor; it is not score 4 because coverage of the domain's visual families is essentially complete rather than having minor gaps.

Completeness

It explicitly answers both questions: the 'what' is the full-screen real-time WebGL/WebGL2 experience with typographic overlay in one index.html, and the 'when' is an explicit 'Use when the brief asks for a... experience' clause with concrete trigger phrases — a direct match to the 5 anchor's exemplar structure. It is not below 5 because neither half is vague or implied.

Trigger Term Quality

The 'Use when' clause quotes eight natural trigger phrases ('WebGL', 'shader', '3D', 'generative', 'GPU', 'interactive canvas', 'hero animation', 'real-time visual') plus 'WebGL2' earlier — good coverage, but common synonyms users actually say such as 'GLSL', 'fragment shader', 'shader background/art', or 'three.js' are absent, so it sits between the 4 and 5 anchors rather than clearly at 5.

Distinctiveness Conflict Risk

The core niche (GPU/WebGL real-time visuals, 'raymarch', 'particle field') is distinct with minimal conflict, matching the 'mostly distinct' anchor. It is not 5 because broader quoted triggers like 'hero animation' and 'interactive canvas' could also plausibly match non-WebGL animation or 2D-canvas skills, creating minor overlap risk with closely related skills.