Conciseness

The body never explains concepts Claude already knows (no library tutorials, no WebGL primer) and is dense with decision guidance, but recurring themes are restated several times: reduced-motion fallbacks appear in the particle section, Interaction Rules, and twice in Output Expectations (lines 62, 97, 108, 111); mobile guidance appears at lines 14, 99, 113, and 114; and the WebGL-vs-SVG justification is repeated across the Overview, Choose/Avoid sections, and Output Expectations. This fits the "mostly efficient but could be tightened" anchor rather than the minor-trims anchor, which requires little to no such repetition.

Actionability

As an instruction-only skill the absence of code is acceptable per the scoring notes, and the guidance is largely followable: the Library Selection section maps each of 12 libraries to concrete use cases, the architecture rules are specific ("cap DPR or quality", "pause offscreen/inactive loops", "define the data contract first: attributes, uniforms, textures, derived values, picking IDs"), and line 13 points to a concrete pre-implementation contract template. Minor gaps remain — a few directives are abstract without any scaffold (e.g. "Keep data-to-scene transforms explicit and reversible") — so it stops short of fully executable guidance.

Workflow Clarity

The 15-step Default Architecture is a clearly ordered progression (renderer choice → projection/transform decisions → primitives → batching → contract → mobile), with checkpoints present: the contract template must be completed "before implementation" (line 13) and includes screenshot QA, and line 86 constrains fallback renderer behavior. It is not a 5 because no explicit validate-and-fix feedback loop is stated in the body itself (QA is delegated to a reference file), and several of the numbered "steps" are standing rules rather than sequenced actions.

Progressive Disclosure

The SKILL.md is a proper overview that pushes detail into eight real, one-level-deep reference files (all eight paths under ./references/ resolve to actual files) organized into Shared theory / Skill references / Templates groups, with in-body pointers to the most load-bearing ones. It is not a 5 because the reference list is bare paths with no one-line description of what each file covers, and six referenced paths are parent-relative (../../references/foundations/* and ../../assets/templates/*) that do not resolve within the provided bundle, weakening navigation reliability.

Specificity

The description names the domain clearly and enumerates ten concrete libraries ("Three.js, raw WebGL, deck.gl, luma.gl, PixiJS, Sigma.js, Plotly WebGL traces, ECharts GL, CesiumJS, Babylon.js"), but the action vocabulary is a single verb — "Render WebGL-accelerated data visualizations" — with no further distinct concrete actions. This matches the anchor for naming the domain with 1-2 concrete actions; it is below the several-actions anchors, which the enumeration of tools alone does not satisfy since tool names are not actions.

Completeness

Both halves are explicit: the what is "Render WebGL-accelerated data visualizations with [ten named libraries]" and the when is a concrete trigger clause — "Use when the visualization needs true spatial structure, dense 2D or 3D GPU rendering, particle or flow animation, volumetric views, or interactive exploration that adds real analytical value." This matches the top anchor of clearly answering both what and when with concrete trigger phrases.

Trigger Term Quality

Strong natural-term coverage: library names users would actually say (Three.js, WebGL, deck.gl, PixiJS, Plotly, Cesium, Babylon.js) plus domain phrases like "particle or flow animation", "volumetric views", "dense 2D or 3D GPU rendering", and "spatial structure". A few common user phrasings are still missing (e.g. "point cloud", "3D scatter", "globe", "flow map"), which keeps it just below the comprehensive-synonyms anchor.

Distinctiveness Conflict Risk

The niche is well defined — GPU/WebGL rendering with named library triggers that no generic skill would claim — giving minimal confusion risk against unrelated skills. It retains minor overlap risk with a closely related general charting/dataviz skill for requests like "make a 3D chart" where both could plausibly fire, which fits the "mostly distinct; minor overlap risk with closely related skills" anchor rather than the clear-niche top anchor.