classmcp

Multi-Framework MCP Server for AI-Optimized CSS Generation

Stop wasting tokens on long utility class strings. Let AI generate code with semantic class names like btn-primary and card - with full SSR safety awareness and optional minification.

Supports Tailwind CSS, Bootstrap 5, UnoCSS, and Tachyons.

The Problem

When AI generates utility-first CSS code, it creates verbose class strings:

<button class="inline-flex items-center justify-center px-4 py-2 bg-blue-600 text-white text-sm font-medium rounded-lg hover:bg-blue-700 focus:outline-none focus:ring-2 focus:ring-blue-500 focus:ring-offset-2 transition-colors">
  Click me
</button>

This wastes:

AI tokens - longer context = higher costs
Your time - harder to read and debug
Bundle size - repeated patterns bloat HTML
SSR safety - easy to accidentally use client-only patterns

The Solution

classmcp provides semantic class names to AI assistants:

<!-- Semantic -->
<button class="btn-primary">Click me</button>

<!-- Or ultra-minified for maximum savings -->
<button class="a">Click me</button>

The AI queries available patterns, uses short names, and you get clean, readable code that's SSR-safe.

Installation

For Claude Desktop

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "classmcp": {
      "command": "npx",
      "args": ["classmcp"]
    }
  }
}

For other MCP clients

npx classmcp

Features

Multi-Framework Support

Switch between CSS frameworks instantly:

set_framework: "tailwind"   # Default
set_framework: "bootstrap"  # Bootstrap 5
set_framework: "unocss"     # UnoCSS
set_framework: "tachyons"   # Tachyons

SSR Safety

Every pattern is marked for server-side rendering compatibility:

get_ssr_info: "modal-overlay"

→ Status: ⚠️ Requires Client JS
→ Warning: Modal visibility controlled by JS
→ Recommendations: Use useEffect to add client-only classes

Filter for SSR-safe patterns only:

list_classes: { ssrSafeOnly: true }

Minification

Generate ultra-short class names for maximum token savings:

get_class: { name: "btn-primary", minified: true }

→ Class: "a" (saves 11 chars per usage)

Custom Patterns

Define your own semantic class names by creating a .classmcp.json file in your project root:

Simple format:

{
  "customPatterns": [
    { "id": "brand-btn", "classes": "px-4 py-2 bg-brand-600 text-white rounded-lg font-semibold" },
    { "id": "pricing-card", "classes": "p-8 border-2 border-gray-100 rounded-2xl shadow-xl" }
  ]
}

With states and metadata:

{
  "customPatterns": [
    {
      "id": "brand-btn",
      "category": "buttons",
      "description": "Brand-colored primary button",
      "classes": {
        "base": "px-4 py-2 bg-brand-600 text-white rounded-lg font-semibold",
        "hover": "hover:bg-brand-700 hover:shadow-md",
        "focus": "focus:ring-2 focus:ring-brand-300"
      }
    }
  ],
  "overrideBuiltins": false,
  "defaultFramework": "tailwind"
}

Config options: | Option | Description | |--------|-------------| | customPatterns | Array of custom pattern definitions | | overrideBuiltins | If true, custom patterns replace built-ins with same ID | | defaultFramework | Default framework to use (tailwind, bootstrap, unocss, tachyons) |

Pattern options: | Field | Required | Description | |-------|----------|-------------| | id | Yes | Unique identifier (e.g., "brand-btn") | | classes | Yes | CSS classes (string or state object with base/hover/focus/active/disabled) | | category | No | Category for organization (defaults to "custom") | | name | No | Human-readable name (defaults to id) | | description | No | Description of when to use | | frameworks | No | Limit to specific frameworks (e.g., ["tailwind"]) | | ssr.safe | No | Whether pattern is SSR-safe |

Alternative config locations:

.classmcp.json (recommended)
classmcp.config.json
package.json under "classmcp" key

After modifying your config, use the reload_config tool to apply changes without restarting.

Available Tools

| Tool | Description | |------|-------------| | set_framework | Set CSS framework (tailwind, bootstrap, unocss, tachyons) | | get_class | Get utility classes for a semantic name | | list_classes | List available classes (filter by category, SSR-safe) | | search_classes | Search for classes by name or description | | generate_css | Generate CSS file with all class definitions | | get_component | Get complete HTML component examples | | get_ssr_info | Check SSR/hydration safety for a pattern | | list_frameworks | List all available frameworks with statistics | | reload_config | Reload custom patterns from config file | | list_custom_patterns | List all user-defined custom patterns |

Class Categories

buttons - btn-primary, btn-secondary, btn-danger, btn-ghost, btn-outline
cards - card, card-bordered, card-header, card-body, card-footer
forms - input, input-error, label, select, checkbox, textarea, toggle
badges - badge-primary, badge-success, badge-warning, badge-danger
alerts - alert-info, alert-success, alert-warning, alert-error
avatars - avatar-sm, avatar-md, avatar-lg
layout - container, flex-center, flex-between, stack, row, grid-2, grid-3
typography - heading-xl, heading-lg, heading-md, text-body, text-muted
navigation - nav, nav-link, nav-link-active
modals - modal, modal-overlay, modal-header, modal-body, modal-footer
tables - table, table-header, th, td, tr-hover
lists - list, list-item, list-item-hover
loading - spinner, skeleton, skeleton-text, skeleton-avatar
dividers - divider, divider-vertical

Usage Example

Ask Claude:

"Create a card with a user profile, showing avatar, name, email, and action buttons"

Claude will use classmcp to generate:

<div class="card">
  <div class="flex-start space-x-4">
    <div class="avatar-lg">JD</div>
    <div class="stack">
      <h3 class="heading-sm">John Doe</h3>
      <p class="text-muted">john@example.com</p>
    </div>
  </div>
  <div class="card-footer">
    <button class="btn-primary">Message</button>
    <button class="btn-secondary">Profile</button>
  </div>
</div>

Setup Your Project

Generate the CSS:

# Ask Claude to use the generate_css tool, or:
npx classmcp generate-css > src/classmcp.css

Import in your CSS:

Tailwind:

@import "tailwindcss";
@import "./classmcp.css";

Bootstrap:

@import "bootstrap/dist/css/bootstrap.min.css";
@import "./classmcp.css";

Token Savings

| Component | Without classmcp | With classmcp | Minified | Savings | |-----------|------------------|---------------|----------|---------| | Button | 180 chars | 12 chars | 1 char | 99% | | Card | 85 chars | 5 chars | 1 char | 99% | | Input | 145 chars | 6 chars | 1 char | 99% | | Modal | 200+ chars | 12 chars | 1 char | 99% |

Over a full page with 50+ components, this adds up to thousands of tokens saved.

SSR Safety Guide

Safe for SSR (no JS needed)

All button variants (hover/focus are CSS pseudo-classes)
All card patterns
Form inputs (base styling)
Typography patterns
Layout utilities
Badges, alerts

Requires Client JS (may cause hydration issues)

modal-overlay - visibility needs JS
toggle - checked state
spinner - animation timing
alert-dismissible - close button

Use ssrSafeOnly: true or check with get_ssr_info when building Next.js/Nuxt/Remix apps.

Framework Statistics

| Framework | Patterns | SSR-Safe | Categories | |-----------|----------|----------|------------| | Tailwind CSS | 70+ | 65+ | 14 | | Bootstrap 5 | 70+ | 65+ | 14 | | UnoCSS | 70+ | 65+ | 14 | | Tachyons | 70+ | 65+ | 14 |

How It Works

┌─────────────┐     ┌─────────────┐     ┌─────────────┐
│   Claude    │────▶│  classmcp   │────▶│  Your Code  │
│             │     │  (MCP)      │     │             │
│ "Make a     │     │             │     │ <button     │
│  button"    │     │ get_class   │     │  class=     │
│             │◀────│ btn-primary │     │  "btn-      │
│             │     │ (SSR-safe)  │     │   primary"> │
└─────────────┘     └─────────────┘     └─────────────┘

AI asks classmcp for available classes
classmcp returns semantic names + SSR safety info
AI generates code using short class names
You add the generated CSS to your project
Your CSS framework compiles it

Related: classpresso

classmcp = AI layer (development time) - helps AI generate clean code
classpresso = Build layer (build time) - optimizes existing code

They're complementary:

Use classmcp when writing new code with AI
Use classpresso to optimize existing/legacy code

License

MIT

Classmcp

Install / Use

README