21st.dev Magic + mcp-use: Complete MCP Integration

21st.dev Magic is a MCP server that Create crafted UI components inspired by the best 21st.dev design engineers..

When integrated with mcp-use, you can:

• Generate crafted UI components using AI design patterns
• Live preview of generated components
• Full TypeScript support for generated components

This guide provides step-by-step instructions to set up 21st.dev Magic in mcp-use, including configuration, examples, and troubleshooting.

What You'll Achieve

After completing this setup:

• 21st.dev Magic will be fully integrated and operational
• You can use 21st.dev Magic tools directly in mcp-use
• All 21st.dev Magic capabilities will be available for your workflows
• Access to 4 different tools

Prerequisites

Before starting, ensure you have:

• 21st.dev account
• API key
• 21st.dev Magic API key for authentication
• mcp-use installed and configured
• Compatible operating system (Python 3.8+, Node.js 16+, pip Installation, npm/yarn Installation)

Installation

Step 1: Install 21st.dev Magic

Manual installation steps:

1. Generate API key from 21st.dev Magic Console
2. Add configuration to IDE-specific JSON config
3. Restart IDE to load MCP server

Configuration

Step 2: Configure mcp-use

1. Open mcp-use settings
2. Navigate to MCP server configuration
3. Add 21st.dev Magic server with appropriate settings
4. Save and restart if needed

Examples

Once configured, you can use 21st.dev Magic in mcp-use:

Create Navigation Bar

Generate a modern responsive navigation component

Ask mcp-use: "/ui create a modern navigation bar with responsive design"

Expected Result: Responsive navigation component with mobile menu, logo placement, and styling

Generate Dashboard Card

Create a dashboard card with metrics display

Ask mcp-use: "/ui design a dashboard card showing user analytics with charts"

Expected Result: Card component with chart integration, metrics display, and responsive layout

Build Form Component

Create a contact form with validation

Ask mcp-use: "/ui create a contact form with validation and modern styling"

Expected Result: Form component with input validation, error states, and submit handling

Design Landing Hero

Generate a landing page hero section

Ask mcp-use: "/ui build a hero section for a SaaS product with CTA buttons"

Expected Result: Hero component with headline, description, call-to-action buttons, and background

Testing Your Setup

1. Launch mcp-use
2. Verify 21st.dev Magic is available in the tools list
3. Test basic 21st.dev Magic functionality

Troubleshooting

Common Issues

API Key Invalid

Symptoms: Authentication errors, Access denied messages, Server connection failures

Cause: Invalid or expired API key

Solution:

• Generate new API key from 21st.dev Magic Console
• Update API_KEY in IDE configuration
• Restart IDE to reload configuration

IDE Not Detecting MCP Server

Symptoms: MCP commands not available, Server not listed in IDE

Cause: Incorrect configuration file or location

Solution:

• Verify config file is in correct location for your IDE
• Check JSON syntax in configuration file
• Restart IDE after configuration changes
• Use CLI installation for automatic setup

Component Generation Fails

Symptoms: Empty responses, Error messages during generation

Cause: Network issues or service limitations

Solution:

• Check internet connectivity
• Verify API key has sufficient quota
• Try simpler prompts initially
• Contact support if issues persist

TypeScript Errors in Generated Code

Symptoms: Type errors, Compilation failures

Cause: Missing dependencies or type definitions

Solution:

• Install required TypeScript dependencies
• Update @types packages
• Configure TypeScript strict mode properly
• Import necessary type definitions

Connection Refused or Server Unreachable

Symptoms: ECONNREFUSED error, Connection timeout, Cannot reach server

Cause: MCP server not running or incorrect URL

Solution:

• Verify MCP server is running and accessible
• Check server URL is correct (protocol, host, port, path)
• Test server URL in browser or with curl to confirm it responds
• Ensure firewall allows connections to server port
• Verify CORS settings if accessing from browser

Import Errors or Module Not Found

Symptoms: ModuleNotFoundError: mcp_use, Cannot find module "mcp-use"

Cause: Package not installed or wrong environment

Solution:

• Verify installation: pip show mcp-use (Python) or npm list mcp-use (JS)
• Ensure using correct Python virtual environment or Node.js project
• Reinstall package: pip install --upgrade mcp-use or npm install mcp-use
• Check package.json or requirements.txt includes mcp-use

Tool Discovery Returns Empty List

Symptoms: list_tools() returns [], No tools available, Tools not found

Cause: MCP server not properly configured or not exposing tools

Solution:

• Verify MCP server is properly initialized and configured
• Check server logs to confirm tools are registered
• Test server directly with MCP inspector or test client
• Ensure server implements MCP protocol correctly
• Verify transport type (HTTP/SSE) matches server configuration

Tool Execution Fails or Returns Errors

Symptoms: Tool call throws exception, Invalid arguments error, Execution timeout

Cause: Incorrect arguments or server-side execution failure

Solution:

• Verify tool arguments match schema definition from list_tools()
• Check required arguments are provided with correct types
• Review server logs for detailed error messages
• Test tool with minimal valid arguments first
• Increase timeout if tool requires longer execution time

LangChain.js Integration Not Working

Symptoms: getLangChainTools() fails, Tools not recognized by agent, Type errors

Cause: Version mismatch or incorrect integration setup

Solution:

• Ensure LangChain.js version is compatible with mcp-use
• Verify TypeScript version meets requirements
• Check tool schema conversion is working correctly
• Use latest versions of both mcp-use and LangChain.js
• Review LangChain.js documentation for agent setup

Transport Type Errors (HTTP vs SSE)

Symptoms: SSE connection fails, HTTP polling not working, Event stream errors

Cause: Mismatch between client transport and server capabilities

Solution:

• Verify server supports the transport type you are using
• Try alternative transport: switch between "http" and "sse"
• Check server documentation for supported transport types
• For SSE, ensure server sends proper Content-Type: text/event-stream
• For HTTP, verify server accepts POST requests with JSON payload

21st.dev Magic not appearing in mcp-use

Symptoms: Server not listed, Tools not available

Cause: Configuration or installation issue

Solution:

• Verify configuration syntax
• Check 21st.dev Magic installation
• Restart mcp-use
• Check logs for error messages

Next Steps

Now that 21st.dev Magic is integrated with mcp-use:

• Explore all 21st.dev Magic capabilities through mcp-use
• Check out other MCP servers that work with mcp-use
• Join the MCP community for tips and support
• Consider contributing to 21st.dev Magic development

Need Help?

• Search for 21st.dev Magic documentation
• Check the mcp-use MCP guide
• Join the MCP community discussions