cvdsafe-mcp

An MCP server that lets an LLM check whether a palette or an image is colorblind-safe, as native tools. Built on opticquiz-cvd (Machado 2009 + CIEDE2000). Runs locally over stdio; nothing leaves your machine.

Tools

• checkPalette — { colors: string[] } → whether the palette stays distinguishable under protan/deutan/tritan, with the conflicting pairs.
• checkImage — { path?, dataUri?, maxColors?, returnSimulated? } → extracts an image's dominant colors and flags the pairs that collapse under colorblindness, each weighted by how much of the image's area they cover. Reads PNG and JPEG. With returnSimulated: true it also hands back the image recolored as a deuteranope sees it.
• fixPalette — { colors: string[] } → an adjusted, colorblind-safe palette that stays near the originals.
• checkContrast — { foreground, background, large? } → the WCAG contrast ratio and whether it passes AA/AAA.
• simulateColor — { color, type } → how a color appears under a given deficiency.

Add it to Claude Desktop

Edit claude_desktop_config.json (Settings → Developer → Edit Config) and add:

{
  "mcpServers": {
    "cvdsafe": {
      "command": "npx",
      "args": ["-y", "cvdsafe-mcp"]
    }
  }
}

Restart Claude Desktop. Then ask, e.g., "Is this palette colorblind-safe: #d7191c, #1a9641, #2166ac? If not, fix it." — or "Is the chart at ./dashboard.png readable for colorblind users?" — and it calls the tools. Same config shape works in Cursor and other MCP clients.

Note

A screening aid, not a legal accessibility (ADA/WCAG) audit. Methods: Machado, Oliveira & Fernandes (2009); Brettel, Viénot & Mollon (1997); CIEDE2000 — https://doi.org/10.5281/zenodo.21310578