intermediate⏱️ 22-32 minutes📅 Updated June 2026

Step-by-step guide to integrate 21st.dev Magic MCP server with fast-agent. Includes ai-powered ui generation and real-time component preview.

21st.dev Magic + fast-agent: 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 fast-agent, 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 fast-agent, 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 fast-agent
  • 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
  • fast-agent installed and configured
  • Compatible operating system (Node.js, Cross-platform, Edge Environments)

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 fast-agent

  1. Open fast-agent 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 fast-agent:

Create Navigation Bar

Generate a modern responsive navigation component

Ask fast-agent: "/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 fast-agent: "/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 fast-agent: "/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 fast-agent: "/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 fast-agent
  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

Poor Performance

Symptoms: Slow startup, High memory usage, Slow tool execution

Cause: Suboptimal configuration or resource constraints

Solution:

  • Tune concurrency and pool size settings
  • Optimize MCP server performance
  • Check system resources and limits
  • Profile application for bottlenecks

Agent Crashes Under Load

Symptoms: Out of memory errors, Process crashes

Cause: Resource limits exceeded

Solution:

  • Reduce concurrency limits
  • Increase memory limits if possible
  • Implement graceful degradation
  • Monitor resource usage patterns

MCP Server Timeouts

Symptoms: Tool execution timeouts, Connection errors

Cause: Server overload or network issues

Solution:

  • Increase timeout values
  • Implement retry logic
  • Scale MCP server infrastructure
  • Use connection pooling and caching

21st.dev Magic not appearing in fast-agent

Symptoms: Server not listed, Tools not available

Cause: Configuration or installation issue

Solution:

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

Next Steps

Now that 21st.dev Magic is integrated with fast-agent:

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

Need Help?

Related Resources

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Need Help?

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21st.dev Magic + fast-agent: MCP Setup Guide (2026)