Coolors MCP

Advanced color operations MCP server with Material Design 3 support, CSS theme matching, image color extraction, and accessibility compliance.

Features

• 🎨 Color Space Conversions - RGB, HSL, HSV, LAB, XYZ, and Google's HCT
• 📏 Perceptual Color Metrics - Delta E (76/94/2000) and HCT-based distance
• 🎭 Material Design 3 - Complete theme generation with tonal palettes
• 🔍 Smart Theme Matching - Find closest CSS variables for any color
• 🖼️ Image Color Extraction - Extract dominant colors using Celebi quantization
• ♿ WCAG Compliance - Automatic contrast ratio checking
• 🔄 CSS Refactoring - Automated legacy color replacement with theme variables
• 🎯 Context-Aware - Different matching strategies for text, background, borders
• 🌈 Advanced Palette Generation - Create palettes with locked colors
• 🎨 Gradient Generation - Smooth gradients with multiple interpolation methods
• 🚫 Dislike Analysis - Detect and fix universally disliked colors
• 👁️ Color-Blindness Simulation - Brettel/Machado matrices for protan/deutan/tritan + accessibility audit
• 🆎 APCA Contrast - WCAG 3 draft contrast (Lc) alongside classic WCAG 2.x ratio
• 🎚️ Tonal Scales & State Colors - Tailwind-style 50–950 scales and hover/active/focus/disabled variants in HCT
• 🧬 Palette Cohesion Score - Quantify visual unity (tone / chroma / hue harmony) with targeted fix suggestions
• 🪪 Semantic Palettes - One brand color → primary/secondary/tertiary + success/warning/error/info in a unified family
• 📦 Palette Export - CSS custom properties, SCSS, Tailwind config, W3C design tokens, JSON

Installation

Method 1: NPX (Recommended)

No installation needed - runs directly:

Claude Desktop Configuration

{
  "mcpServers": {
    "coolors": {
      "command": "npx",
      "args": ["-y", "@trishchuk/coolors-mcp"]
    }
  }
}

Claude Code Configuration

claude mcp add coolors --npm-package @trishchuk/coolors-mcp

Method 2: NPM Install

npm install @trishchuk/coolors-mcp

Method 3: From Source

git clone https://github.com/x51xxx/coolors-mcp
cd coolors-mcp
pnpm install
pnpm run build

Quick Start

Run as MCP Server

# Run the built server
node dist/bin/server.js

# Or use with MCP Inspector for testing
npx fastmcp inspect src/bin/server.ts

Configure with Claude Desktop

Add to your Claude Desktop configuration:

{
  "mcpServers": {
    "coolors": {
      "command": "node",
      "args": ["/path/to/coolors-mcp/dist/bin/server.js"]
    }
  }
}

Available Tools

Core Color Operations

convert_color

Convert colors between formats (hex, rgb, hsl, lab, hct).

{
  "color": "#6750a4",
  "to": "hct"
}
// Output: "hct(258.1, 47.3, 41.2)"

color_distance

Calculate perceptual distance between colors.

{
  "color1": "#6750a4",
  "color2": "#7f67be",
  "metric": "deltaE2000"
}
// Output: "Distance: 8.45"

check_contrast

Check contrast between two colors. Supports the WCAG 2.x luminance ratio (default), APCA Lc (WCAG 3 draft), or both side-by-side.

{
  "foreground": "#000000",
  "background": "#ffffff",
  "algorithm": "both"  // "wcag" (default) | "apca" | "both"
}
// Output: WCAG 21.00:1 + APCA Lc 106.0

adjust_color

Lighten / darken / saturate / desaturate / grayscale / invert / mix a color.

{
  "color": "#6750a4",
  "operation": "mix",
  "with": "#ff6b6b",
  "amount": 0.5  // weight (0-1) for mix, percent (0-100) for the others
}

Palette Generation

generate_palette

Generate color palettes (monochromatic, analogous, complementary, triadic, tetradic).

{
  "baseColor": "#6750a4",
  "type": "analogous",
  "count": 5
}

generate_palette_with_locks

Generate palettes while preserving specific colors.

{
  "lockedColors": ["#6750a4", "#ff6b6b"],
  "totalColors": 7,
  "mode": "harmony",  // or "contrast", "gradient"
  "colorSpace": "lab"  // or "hsl"
}

generate_gradient

Create smooth gradients with advanced interpolation.

{
  "colors": ["#6750a4", "#ff6b6b"],
  "steps": 10,
  "interpolation": "lab",  // or "hsl", "rgb", "lch", "hct"
  "easing": "ease-in-out",  // or "linear", "ease-in", "ease-out"
  "format": "css-linear"  // or "array", "hex", "css-radial"
}

Material Design 3

generate_material_theme

Generate complete Material Design 3 color theme.

{
  "sourceColor": "#6750a4",
  "includeCustomColors": true
}

generate_tonal_palette

Create Material Design tonal palettes.

{
  "color": "#6750a4",
  "tones": [0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 95, 99, 100]
}

harmonize_colors

Harmonize multiple colors to work together.

{
  "colors": ["#6750a4", "#ff6b6b", "#4ecdc4"],
  "method": "harmonize",  // or "blend", "temperature"
  "factor": 0.5
}

CSS Theme Matching

match_theme_color

Find closest theme variable for any color.

{
  "color": "#6850a0",
  "themeCSS": ":root { --color-primary-40: #6750a4; }",
  "context": "background",
  "minConfidence": 70
}

refactor_css_with_theme

Automatically refactor CSS to use theme variables.

{
  "css": ".button { background: #6750a4; }",
  "themeCSS": ":root { --color-primary-40: #6750a4; }",
  "preserveOriginal": true,
  "generateReport": true
}

generate_theme_css

Generate CSS custom properties for a complete theme.

{
  "sourceColor": "#6750a4",
  "prefix": "color",
  "includeTones": [0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 95, 99, 100]
}

Image Color Extraction

extract_image_colors

Extract dominant colors from images using Celebi quantization.

{
  "imageData": {
    "data": [/* RGBA array */],
    "width": 1920,
    "height": 1080
  },
  "maxColors": 5,
  "quality": "high",
  "format": "json"
}

generate_theme_from_image

Generate Material Design theme from image colors.

{
  "imageData": {/* image data */},
  "isDark": false,
  "includeCustomColors": true
}

Visual Cohesion

generate_tonal_scale

Build a Tailwind-style 50/100/.../900/950 scale from one seed color. Uses HCT so steps are perceptually even regardless of hue.

{
  "seed": "#6750a4",
  "name": "brand",        // CSS variable base name
  "chromaBoost": 1,       // multiplier on seed chroma
  "stops": [50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 950]
}

generate_state_colors

Derive interaction states (hover/active/pressed/focus/disabled/selected) from a base color with consistent tonal deltas.

{
  "base": "#6750a4",
  "isDark": false   // true to lighten on hover instead of darkening
}

analyze_palette_consistency

Score visual cohesion of a palette: tonal step uniformity, chroma spread, hue harmony, plus a single 0–100 score and targeted suggestions.

{
  "colors": ["#6750a4", "#7f67be", "#a48dc8", "#ff0000"]
}
// Output: cohesion 77/100 + outlier #ff0000 (chroma 105 vs avg 60)

generate_semantic_palette

From one brand color, generate primary/secondary/tertiary + success/warning/error/info with normalized chroma & tone so every color feels like part of the same family.

{
  "brand": "#6750a4",
  "isDark": false
}

Accessibility & Color Blindness

simulate_color_blindness

Simulate how colors appear to viewers with protanopia / deuteranopia / tritanopia (and the milder anomaly forms, plus achromatopsia). Uses Machado-style linear-sRGB confusion-line matrices.

{
  "colors": ["#e63946", "#2a9d8f"],
  "types": ["protanopia", "deuteranopia"]  // optional, defaults to all 7
}

check_palette_accessibility

Audit a palette for color-blind friendliness — flags pairs of colors that become indistinguishable under each CVD type.

{
  "colors": ["#e63946", "#2a9d8f", "#264653", "#f4a261"],
  "indistinguishableThreshold": 10  // ΔE2000 below which colors collide
}

Palette Export

export_palette

Export a palette as CSS custom properties, SCSS variables, a Tailwind config snippet, W3C design tokens, or JSON.

{
  "colors": ["#fef3c7", "#fde68a", "#fcd34d"],
  "format": "tailwind",   // "css" | "scss" | "tailwind" | "tokens" | "json"
  "prefix": "amber",
  "names": ["50", "100", "200"]   // optional, default uses 50/100…900 scale
}

Color Psychology

analyze_color_likability

Check if colors fall in universally disliked ranges.

{
  "color": "#6b6b00"  // Dark yellow-green
}
// Output: Analysis with fix suggestions

fix_disliked_colors_batch

Fix multiple disliked colors automatically.

{
  "colors": ["#6b6b00", "#7a7a10", "#808020"],
  "strategy": "hue_shift"  // or "desaturate", "brighten"
}

Color Science

HCT Color Space

Google's HCT (Hue, Chroma, Tone) color space provides:

• Hue (0-360°): Color wheel position
• Chroma (0-150): Color intensity
• Tone (0-100): Lightness with guaranteed WCAG contrast

Key benefits:

• Tone difference of 40 = 3:1 contrast ratio
• Tone difference of 50 = 4.5:1 contrast ratio
• Perceptually uniform for UI design

Interpolation Methods

Different color spaces for gradient generation:

• RGB: Simple but can produce muddy colors
• HSL: Good for hue-based transitions
• LAB: Perceptually uniform brightness
• LCH: Cylindrical LAB, smooth hue transitions
• HCT: Material Design optimized

Theme Matching Algorithm

Multi-factor scoring system:

1. Perceptual Distance (60%) - HCT-based similarity
2. Semantic Context (20%) - Role appropriateness
3. Accessibility (20%) - Contrast compliance

Development

This project uses pnpm. Install it once with npm i -g pnpm or corepack enable.

# Install dependencies
pnpm install

# Build the project
pnpm run build

# Run tests
pnpm test

# Format code
pnpm run format

# Lint
pnpm run lint

Architecture

src/
├── bin/
│   └── server.ts               # MCP server entry
├── tools/                      # Tool implementations
│   ├── color-conversion.tool.ts
│   ├── color-distance.tool.ts
│   ├── contrast-checker.tool.ts
│   ├── palette-generator.tool.ts
│   ├── palette-with-locks.tool.ts
│   ├── gradient-generator.tool.ts
│   ├── material-theme.tools.ts
│   ├── theme-matching.tools.ts
│   ├── image-extraction.tools.ts
│   └── dislike-analyzer.tool.ts
├── color/                      # Core color utilities
│   ├── conversions.ts          # Color space conversions
│   ├── metrics.ts              # Distance calculations
│   ├── utils.ts                # Color utilities
│   ├── hct/                   # HCT color space
│   ├── quantize/               # Celebi quantization
│   ├── score/                  # Color scoring
│   └── dislike/                # Dislike analysis
└── theme/                      # Theme system
    ├── parser.ts               # CSS parsing
    ├── matcher.ts              # Variable matching
    └── refactor.ts             # CSS refactoring

Use Cases

Design System Migration

Convert hardcoded colors to CSS variables with confidence scores.

Accessibility Compliance

Ensure all color combinations meet WCAG AA/AAA standards.

Material Design Adoption

Generate complete Material Design 3 themes with tonal palettes.

Brand Color Harmonization

Create cohesive palettes that work well together.

Image-Based Theming

Extract colors from logos or photos to generate matching themes.

Gradient Design

Create smooth, perceptually uniform gradients for modern UIs.

Contributing

Contributions welcome! Please ensure:

• Tests pass (pnpm test)
• Code is formatted (pnpm run format)
• Type checking passes (pnpm run lint)

License

MIT © Taras Trishchuk

Credits

• Built with MCP SDK by Anthropic
• Incorporates algorithms from Material Color Utilities by Google
• HCT color space developed for Material Design 3
• Celebi quantization algorithm for optimal color extraction