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Pay from Agents SDK

The Agents SDK includes an MCP client that can pay for x402-protected tools. Use it from your Agents or any MCP client connection.

TypeScript
import { Agent } from "agents";
import { withX402Client } from "agents/x402";
import { privateKeyToAccount } from "viem/accounts";


export class MyAgent extends Agent {
  // Your Agent definitions...


  async onStart() {
    const { id } = await this.mcp.connect(`${this.env.WORKER_URL}/mcp`);
    const account = privateKeyToAccount(this.env.MY_PRIVATE_KEY);


    this.x402Client = withX402Client(this.mcp.mcpConnections[id].client, {
      network: "base-sepolia",
      account,
    });
  }


  onPaymentRequired(paymentRequirements): Promise<boolean> {
    // Your human-in-the-loop confirmation flow...
  }


  async onToolCall(toolName: string, toolArgs: unknown) {
    // The first parameter is the confirmation callback.
    // Set to `null` for the agent to pay automatically.
    return await this.x402Client.callTool(this.onPaymentRequired, {
      name: toolName,
      arguments: toolArgs,
    });
  }
}

For a complete working example, see x402-mcp on GitHub ↗.

Environment setup

Store your private key securely:

Terminal window
# Local development (.dev.vars)
MY_PRIVATE_KEY="0x..."


# Production
npx wrangler secret put MY_PRIVATE_KEY

Use base-sepolia for testing. Get test USDC from the Circle faucet ↗.