components-build-mcp

An MCP (Model Context Protocol) server that implements the components.build specification for grading, generating, and validating UI components.

About

This MCP server provides AI assistants with tools to:

• Access the complete components.build specification - The full documentation embedded and searchable
• Grade components - Validate any component against the spec's rules
• Generate compliant components - Create new components that follow all best practices
• Search documentation - Find specific patterns, rules, or concepts

The components.build specification is an open-source standard for building modern, composable, and accessible UI components, co-authored by Hayden Bleasel and shadcn.

Framework Support

Feature	Frameworks Supported
Specification	Framework-agnostic
Grading	Framework-agnostic (React, Vue, Svelte, Angular, etc.)
Templates	React + TypeScript

The grading rules check for universal patterns (accessibility, composition, data attributes) that apply to any framework.

Installation

For Claude Code / Claude Desktop

npm install -g components-build-mcp

Add to your Claude configuration (~/.claude/claude_desktop_config.json):

{
  "mcpServers": {
    "components-build": {
      "command": "components-build-mcp"
    }
  }
}

For Local Development

git clone https://github.com/getlokiui/components-build-mcp.git
cd components-build-mcp
npm install
npm run build

Add to Claude config with full path:

{
  "mcpServers": {
    "components-build": {
      "command": "node",
      "args": ["/path/to/components-build-mcp/dist/index.js"]
    }
  }
}

Available Tools

Documentation Tools

Tool	Description
get_specification	Get the full spec or a specific section
search_specification	Search for terms like "aria", "CVA", "data-slot"
list_specification_sections	List all 16 documentation sections

Grading & Validation Tools

Tool	Description
grade_component	Grade code and get detailed feedback with score
check_compliance	Quick pass/fail check (threshold: 80/100)
get_rules	Get grading rules by category
get_rule	Get details about a specific rule
list_rules	List all rules with severity and weight

Generation Tools

Tool	Description
generate_component	Generate a compliant component from templates
get_template	Get reference templates (button, card, input, etc.)
get_quick_reference	Get the cheat sheet

Usage Examples

Once configured, ask your AI assistant:

"Show me the components.build spec section on accessibility"

"Grade this component against the spec:
export const Button = ({ children }) => <button>{children}</button>"

"Generate a Card component with composable sub-components"

"Search the spec for keyboard navigation patterns"

"What rules does the grader check for?"

Specification Sections

The complete components.build specification includes:

Section	Description
overview	Introduction and purpose
definitions	Terminology (Primitive, Component, Block, etc.)
principles	Core principles (Composability, Accessibility, etc.)
composition	Root/Trigger/Content pattern
accessibility	Complete a11y guide
designTokens	CSS variables and theming
state	Controlled/uncontrolled state
styling	cn(), CVA, tailwind-merge
types	TypeScript patterns
polymorphism	The "as" prop
asChild	Radix Slot pattern
dataAttributes	data-state/data-slot patterns
docs	Documentation standards
registry	shadcn CLI distribution
marketplaces	Component marketplaces
npm	NPM distribution

Grading Rules

Components are graded on:

• Types - Extending HTML props, exporting types, spreading props correctly
• Styling - Using cn() utility, class order, design tokens
• Accessibility - ARIA attributes, keyboard navigation, semantic HTML
• Composition - Single element wrapping, composable patterns
• State - Supporting controlled and uncontrolled usage
• Naming - Following conventions (Root, Trigger, Content, etc.)

HTTP API

A Vercel-compatible HTTP API is also available for non-MCP usage:

# Deploy to Vercel
cd components-build-mcp
vercel --prod

Endpoints:

• GET /?action=rules - Get all rules
• POST /?action=grade - Grade component code
• POST /?action=generate - Generate component
• GET /?action=quick-reference - Get cheat sheet

Credits

This project implements the components.build specification.

The specification is:

• Copyright 2023 Vercel, Inc.
• Co-authored by Hayden Bleasel and shadcn
• Licensed under Apache License 2.0

This MCP server is a community project by Audrey Klammer and is not officially affiliated with or endorsed by Vercel, Inc.

License

Apache License 2.0 - See LICENSE for details.

Contributing

Contributions are welcome! Please read the components.build specification first to understand the patterns and rules.

Links

• components.build - The specification
• shadcn/ui - Reference implementation
• Radix UI - Primitives library
• getlokiui - Component library built on this spec