A
licenseNot graded
qualityD
maintenanceProvides comprehensive color conversion, manipulation, analysis, and WCAG accessibility tools supporting multiple formats (hex, rgb, hsl, oklch, oklab) for design systems and web development.
23 npm
2
MIT
opticquiz-mcp
OpticQuiz MCP servers
Two MCP servers that let an assistant check and see color the way a colorblind person does — built on a published, open-access color-vision method rather than a rule of thumb.
Both are listed in the official Model Context Protocol registry.
cvdsafe-mcp — check it
tool | what it does |
| Whether a set of colors stays distinguishable under protanopia, deuteranopia and tritanopia — with the conflicting pairs named |
| Extracts an image's dominant colors and flags the pairs that collapse, each weighted by how much of the image they cover. PNG + JPEG |
| N colorblind-safe colors, seeded with Okabe–Ito. Never returns an unsafe one |
| Repairs a failing palette, staying close to the originals |
| WCAG contrast ratio, AA/AAA |
| One color under a chosen deficiency |
Related MCP server: huetension mcp
colorblind-mcp — see it
tool | what it does |
| Recolors a PNG/JPEG the way a deficiency renders it, and returns the image |
| Generates an Ishihara-style pseudoisochromatic test plate and returns it |
| One color under all three deficiencies at once |
| A single color under one deficiency, with severity |
Install
Add to claude_desktop_config.json (Settings → Developer → Edit Config):
{
"mcpServers": {
"cvdsafe": { "command": "npx", "args": ["-y", "cvdsafe-mcp"] },
"colorblind": { "command": "npx", "args": ["-y", "colorblind-mcp"] }
}
}Restart, then ask: "Is this palette colorblind-safe: #d7191c, #1a9641, #2166ac?" or "Show me ./dashboard.png the way a deuteranope sees it." Same config shape works in Cursor and other MCP clients.
The method
Colors are simulated with the Machado, Oliveira & Fernandes (2009) deficiency matrices and
compared with CIEDE2000. The method is published open access —
doi.org/10.5281/zenodo.21310578 — and the same engine
ships as installable packages (cvdsafe, cvdsim on PyPI and npm), so any answer these servers
give can be reproduced outside them.
Everything runs locally over stdio. Nothing leaves your machine; images are read from your disk and returned in the response.
Not a legal audit
These check one axis of accessibility — whether colors stay distinguishable under color-vision deficiency. That is not a full WCAG or ADA conformance audit, and passing does not make a product compliant.
Part of OpticQuiz · methodology & disclosure
Available Tools
6 toolscheckContrastCheck text/background contrast against WCAGA
Check whether a foreground color is legible on a background color per WCAG 2.x contrast ratios. Returns the ratio (1-21) and whether it passes AA and AAA. Set large=true for text >=18pt (or 14pt bold). This is the legibility axis, separate from color-blindness.
Inputs: background (required), foreground (required), large.
checkImageCheck an image for colorblind-safetyA
Check whether the colors in an image, chart, screenshot or mockup stay distinguishable for people with color-vision deficiency. Extracts the image's dominant colors, simulates protanopia, deuteranopia and tritanopia, and flags the color pairs that collapse into each other — each with how much of the image's area those colors cover, so a conflict between two large regions ranks above one between two specks. Reads PNG and JPEG. Pass path for a local file, or a base64 dataUri. Set returnSimulated=true to also get back the image as a deuteranope sees it. A screening aid, not a legal (ADA/WCAG) audit.
Inputs: path, dataUri, maxColors, simulateType, +1 more.
checkPaletteCheck a color palette for colorblind-safetyA
Check whether a set of colors stays distinguishable for people with color-vision deficiency (colorblindness). Simulates protanopia, deuteranopia and tritanopia and flags the pairs whose perceptual difference collapses under simulation. A screening aid, not a legal accessibility (ADA/WCAG) audit.
Inputs: colors (required).
fixPaletteFix a palette to be colorblind-safeA
Take a set of colors that fails the colorblind-safety check and return an adjusted set that passes, staying as close to the originals as possible. Conflicting colors are separated in lightness (the axis color-vision deficiency preserves). Returns the new colors, how far each moved, and whether it fully passes.
Inputs: colors (required).
generateSafePaletteGenerate a colorblind-safe paletteA
Return N colorblind-safe hex colors — distinct to each other under protanopia, deuteranopia and tritanopia. Seeded with the Okabe-Ito palette and safely extended above eight. Use when asked for accessible / colorblind-safe / colorblind-friendly colors for a chart, plot, map or UI. Never returns an unsafe color.
Inputs: count (required).
simulateColorSimulate a color under colorblindnessB
Return how a single hex color appears to someone with a given type of color blindness (protan, deutan, or tritan).
Inputs: type (required), color (required).
Tool Schema Changelog
Recent tool additions, removals, and schema changes observed during successful MCP inspections.
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TDQS
A4.1/5.0
Scored across 6 tools
Disambiguation5/5
Each tool has a clearly distinct purpose: checkContrast handles WCAG legibility, checkPalette and checkImage handle colorblind distinguishability for sets and images respectively, generateSafePalette creates safe colors, fixPalette repairs failing sets, and simulateColor shows one color under CVD. The descriptions explicitly separate the axes (legibility vs. colorblindness) and input types, so misselection is unlikely.
Naming Consistency5/5
All six tools follow a consistent camelCase verb+noun pattern: checkContrast, checkImage, checkPalette, generateSafePalette, simulateColor, fixPalette. The verbs are standard and predictable, with no mixed conventions or vague names.
Tool Count5/5
Six tools is well-scoped for a color-accessibility domain, covering checking, generating, fixing, and simulating without redundancy. Each tool earns its place and the count is neither thin nor bloated.
Completeness5/5
The surface covers the full workflow: checking contrast, checking palettes and images for CVD, simulating single colors, generating safe palettes, and repairing failing palettes. No obvious gaps remain for the stated color-accessibility purpose.
Maintenance
ActivityStale
ResponsivenessLimited data
Related MCP Connectors
WCAG color contrast checks, nearest accessible color, CSS color conversion and palette pair checks.
Solve, audit and simulate colorblind-safe chart palettes. WCAG contrast, OKLab ΔE. Read-only.
Contrast checks with fixes, OKLCH harmonies, palettes, color-blind previews and code export.
Convert colours between hex, RGB, HSL, OKLCH and CMYK, and compute harmonies.
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