Welcome to the Storybook MCP Addon monorepo! This project enables AI agents to work more efficiently with Storybook by providing an MCP (Model Context Protocol) server that exposes UI component information and development workflows.

This monorepo contains two main packages:

• @storybook/mcp - Standalone MCP library for serving Storybook component knowledge (can be used independently)
• @storybook/addon-mcp - Storybook addon that runs an MCP server within your Storybook dev server, and includes the functionality of @storybook/mcp from your local Storybook

Each package has its own README with user-facing documentation. This document is for contributors looking to develop, test, or contribute to these packages.

• Node.js 24+ - The project requires Node.js 24 or higher (see .nvmrc)
• pnpm 10.19.0+ - Strict package manager requirement (enforced in package.json)

# Use the correct Node version
nvm use

# Install pnpm if you don't have it
npm install -g pnpm@10.19.0

# Clone the repository
git clone https://github.com/storybookjs/mcp.git
cd addon-mcp

# Install all dependencies (for all packages in the monorepo)
pnpm install

# Build all packages
pnpm build

# Start development mode (watches for changes in all packages)
pnpm dev

# Run unit tests
pnpm test

# Run Storybook with the addon for testing
pnpm storybook

The pnpm storybook command starts:

• The internal test Storybook instance on http://localhost:6006
• The addon in watch mode, so changes are reflected automatically
• MCP server available at http://localhost:6006/mcp

The dev command runs all packages in watch mode, automatically rebuilding when you make changes:

# Start development mode for all packages
pnpm dev

This runs:

• packages/addon-mcp in watch mode (using tsdown --watch)
• packages/mcp in watch mode (using Node's --watch flag)

Note: Running pnpm storybook automatically starts the addon in dev mode alongside Storybook. In this mode, making changes to addon-mcp will automatically restart Storybook. So you typically only need one command:

# This is usually all you need - starts Storybook AND watches addon for changes
pnpm storybook

For more advanced workflows, you can run dev mode for a specific package:

# Watch only the addon package
pnpm --filter @storybook/addon-mcp dev

# Watch only the mcp package
pnpm --filter @storybook/mcp dev

# Build all packages
pnpm build

# Build a specific package
pnpm --filter @storybook/addon-mcp build
pnpm --filter @storybook/mcp build

# Watch tests
pnpm test

# Run tests
pnpm test run

# Run tests with coverage
pnpm test run --coverage

Use the MCP Inspector to debug and test MCP server functionality:

# Launches the MCP inspector (requires Storybook to be running)
pnpm inspect

This uses the configuration in .mcp.inspect.json to connect to your local MCP servers.

Alternatively, you can also use these curl comamnds to check that everything works:

# test that the mcp server is running
# use port 6006 to test the addon-mcp server instead
curl -X POST \
  http://localhost:13316/mcp      \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "tools/list",
    "params": {}
  }'

# test a specific tool call
curl -X POST http://localhost:13316/mcp \
  -H "Content-Type: application/json" \
  -d '{
    "jsonrpc": "2.0",
    "id": 2,
    "method": "tools/call",
    "params": {
      "name": "list-all-components",
      "arguments": {}
    }
  }'

You can start the Storybook with

pnpm storybook

This will build everything and start up Storybook with addon-mcp, and you can then connect your coding agent to it at http://localhost:6006/mcp and try it out.

# Format all files
pnpm format

# Check formatting without changing files
pnpm format --check

Always include file extensions in relative imports:

// ✅ Correct
import { foo } from './bar.ts';

// ❌ Wrong
import { foo } from './bar';

• JSON imports use the import attributes syntax:

import pkg from '../package.json' with { type: 'json' };

This project uses Changesets for version management:

# 1. Create a changeset describing your changes
pnpm changeset

When you create a PR, add a changeset if your changes should trigger a release:

• Patch: Bug fixes, documentation updates
• Minor: New features, backward-compatible changes
• Major: Breaking changes

We welcome contributions! Here's how to get started:

1. Fork the repository and create a feature branch
2. Make your changes following the code conventions above
3. Test your changes using the internal Storybook instance
4. Create a changeset if your changes warrant a release
5. Submit a pull request with a clear description

• Code builds without errors (pnpm build)
• Tests pass (pnpm test)
• Code is formatted (pnpm format)
• Changes tested with MCP inspector or internal Storybook
• Changeset created if necessary (pnpm changeset)

• Ideas & Feature Requests: Start a discussion
• Bug Reports: Open an issue
• Questions: Ask in GitHub Discussions

MIT - See LICENSE for details

Note: This project is experimental and under active development. APIs and architecture may change as we explore the best ways to integrate AI agents with Storybook.