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X402 MCP

Flask Status: Distilling 🧪

X402 MCP Direct Integration

Overview​

X402 MCP bridges the Model Context Protocol with the X402 payment protocol, enabling micropayments for AI tool invocations. This integration allows developers to monetize their MCP tools with instant, automatic stablecoin payments directly over HTTP.

The system enables programmatic machine-to-machine transactions without accounts or complex authentication, making it ideal for AI agents that need to pay for premium tools and services.

Key Features​

Instant Micropayments​

  • Pay-per-use model for MCP tools
  • Automatic USDC payments on Base network
  • No accounts or authentication required
  • Settlement happens transparently during tool invocation

Flexible Architecture​

The library supports multiple deployment patterns:

Client Proxy Architecture - Bridge non-payment-aware clients to payment-required servers
Server Proxy Architecture - Monetize existing API-key-protected services

Use Cases​

For Tool Developers​

  • Monetize your MCP tools with minimal setup
  • Set custom pricing per tool invocation
  • Receive instant payments in USDC
  • No payment infrastructure needed

For AI Applications​

  • Access premium tools programmatically
  • Pay only for what you use
  • Automatic payment handling
  • Works with Claude Desktop and other MCP clients

For Service Providers​

  • Wrap existing APIs with micropayment layer
  • Convert API-key services to pay-per-use
  • Create new revenue streams
  • Maintain full MCP protocol compatibility

How It Works​

  1. Client requests a tool invocation - Standard MCP request flow
  2. Server responds with payment requirement - HTTP 402 status with payment details
  3. Client constructs payment - Automatic USDC transaction on Base
  4. Server verifies and executes - Tool runs after payment confirmation
  5. Results returned to client - Standard MCP response with settlement info

Learn more about the technical implementation

Quick Demo​

Try it with your LLM by adding this MCP server configuration:

{
  "mcpServers": {
    "x402": {
      "command": "npx",
      "args": [ "@civic/x402-mcp" ],
      "env": {
        "PRIVATE_KEY": "Your wallet private key",
        "TARGET_URL": "https://x402-mcp.fly.dev/mcp"
      }
    }
  }
}

The demo uses Base Sepolia testnet. Get test ETH and USDC from the Coinbase developer platform faucet.

Technical Details​

X402 Protocol​

X402 revives the HTTP 402 Payment Required status code to enable programmatic payments. Developed by Coinbase, it creates a simple flow for instant, on-chain stablecoin payments. Learn more at the X402 documentation.

MCP Integration​

The library wraps MCP's streaming HTTP transport to intercept tool calls and handle payment flows transparently, maintaining full protocol compatibility while adding monetization capabilities. See the integration architecture for implementation details.

Open Source​

X402 MCP is open source and available on GitHub. Contributions and feedback are welcome!

Getting Started​

Ready to monetize your MCP tools or access payment-required services? Check out our implementation guide or contact us for support.