Conciseness

The ~820-line body inlines ~250 lines of pattern code and a ~60-line scales reference that duplicate the existing references/d3-patterns.md and references/scale-reference.md, and the boilerplate setup (select, clear, margins, groups) repeats nearly verbatim three times. This goes beyond "some unnecessary explanation" — several sections are padded or duplicated, matching anchor 2.

Actionability

Concrete, executable d3 v7 code throughout (full copy-paste-ready functions for bar chart, chord diagram, heatmap, force network, with data-format comments), plus actionable interactivity, transition, and troubleshooting sections. Not 5: several snippets (line chart, pie, scatter) reference undefined surrounding scope (xScale, g, width) and are fragments rather than runnable code.

Workflow Clarity

The core workflow is a clearly numbered sequence (setup → integration pattern → structure → responsive sizing) with data guards ("if (!data || data.length === 0) return;"), returned cleanup functions for resize listeners/observers, and a Common issues troubleshooting section. Not 5: no explicit validation checkpoints or feedback loops; the domain is non-destructive so the cap does not apply.

Progressive Disclosure

The Resources section clearly signals one-level-deep references (d3-patterns.md, scale-reference.md, colour-schemes.md) and they exist, but bulk pattern/scale content that should live in those files is inlined and duplicated in the body. Additionally, the body cites "chart-template.js" and "interactive-template.js" while the actual assets are .jsx files — a filename mismatch. Content that should be separate is inline, matching anchor 3; not 4 because the duplication is extensive and asset references are inaccurate.

Specificity

Lists several concrete deliverables — "creating custom charts, graphs, network diagrams, geographic visualisations, or any complex SVG-based data visualisation" with "fine-grained control over visual elements, transitions, or interactions" — but the actions are largely variations of a single verb (creating), leaving minor coverage gaps versus the comprehensive multi-action anchor.

Completeness

Explicitly answers both: what ("Creating interactive data visualisations using d3.js") and when ("This skill should be used when creating custom charts… Use this for bespoke visualisations beyond standard charting libraries") with concrete trigger phrases. Not 4: the when-clause is fully explicit with specific triggers, matching the top anchor's structure.

Trigger Term Quality

Good natural keyword coverage ("charts, graphs, network diagrams, d3.js, React, Vue, Svelte, vanilla JavaScript") that users would actually say, but a few natural terms are missing — notably the American spelling "visualizations", plus "plot", "dashboard", and "data viz".

Distinctiveness Conflict Risk

Scoped to a clear d3.js/SVG niche and explicitly contrasted with "standard charting libraries", keeping it mostly distinct. Not 5: "creating custom charts, graphs" are broad triggers that overlap general charting/dataviz skills.