Machine readers · MCP
The Chart Color System as a tool.
The engine behind this app is available to AI assistants as a read-only Model Context Protocol server. An assistant that connects to it can solve a chart palette around your brand colors, audit colors you already have, show what a colorblind reader sees, and build sequential or diverging scales, with the engine's measurements and honesty notes instead of a guess.
Endpoint
https://chart-color-mcp.vercel.app/mcp
Streamable HTTP, stateless: JSON-RPC 2.0 over POST with Accept: application/json, text/event-stream. No authentication, no accounts, read-only. In Claude: Settings, Connectors, add custom connector, paste the URL. In Claude Code: claude mcp add --transport http chart-colors https://chart-color-mcp.vercel.app/mcp.
Tools
| Tool | What it returns |
|---|---|
solve_palette | A categorical palette of n colors with your anchors kept exactly in slot order, the worst pair distances under normal and colorblind vision, the engine's relaxation notes, a full audit against your background, and a link that opens it in the app. Says so plainly above six slots, the honest cap. |
audit_palette | Pass, warn or fail for colors you already have: pairwise OKLab separation under normal vision, deuteranopia, protanopia, tritanopia and achromatopsia, plus WCAG 2.2 non-text contrast of every color against the background. |
simulate_palette | Each color as seen under each vision mode (published Machado 2009 matrices), so the assistant can describe or render the palette as a colorblind reader sees it. |
build_ramp | An evenly spaced perceptual scale, sequential or diverging, with a background-contrast audit. |
The engine behind it
The same code the app runs, published as chart-color-system on npm. Every result reports the engine version. Distances are OKLab ΔE; contrast is WCAG 2.2.
Three things to ask
- "Give me six chart colors that keep #0057b8 and stay distinguishable for deuteranopes on a white background."
- "Audit these five colors on a dark dashboard background and tell me which pair fails."
- "Build a seven-step diverging scale from red through neutral to blue."
Privacy
The server keeps no accounts and stores nothing from a conversation. Requests are processed and discarded.