@Arispay/Payagent

MCP server for ArisPay-delegated x402 USDC payments. Lets AI agents call paid APIs and settle HTTP 402 challenges with USDC on Base — no private keys ever live in this process.

Works with Claude Desktop, Cursor, Windsurf, or any MCP client. A thin wrapper around the payagent SDK.

Setup

1. Provision an agent at payagent.arispay.app. You'll get:
   • A CDP-managed wallet address to fund with USDC on Base
   • An ARISPAY_AGENT_KEY (returned exactly once — store it securely)
2. Fund the wallet with USDC on Base.
3. Add the MCP server to your client config:

Claude Desktop

Edit ~/Library/Application Support/Claude/claude_desktop_config.json:

{
  "mcpServers": {
    "arispay": {
      "command": "npx",
      "args": ["-y", "@arispay/payagent-mcp"],
      "env": {
        "ARISPAY_AGENT_KEY": "ap_live_...",
        "PAYAGENT_WALLET": "0x..."
      }
    }
  }
}

Cursor

Edit .cursor/mcp.json in your project:

{
  "mcpServers": {
    "arispay": {
      "command": "npx",
      "args": ["-y", "@arispay/payagent-mcp"],
      "env": {
        "ARISPAY_AGENT_KEY": "ap_live_...",
        "PAYAGENT_WALLET": "0x..."
      }
    }
  }
}

Windsurf

Edit ~/.codeium/windsurf/mcp_config.json with the same pattern.

Environment Variables

Variable	Required	Default	Description
ARISPAY_AGENT_KEY	Yes	—	Agent-scoped API key from payagent.arispay.app
ARISPAY_URL	No	https://api.arispay.app	ArisPay API base URL
PAYAGENT_WALLET	No	—	Wallet address (for check_wallet tool output)

Tools

pay_api

Make an HTTP request to a paid API. Automatically handles HTTP 402 payment challenges via ArisPay-delegated signing.

Parameters:

• url (string, required) — The API endpoint URL
• method (string, default: "GET") — HTTP method
• headers (object, optional) — Additional HTTP headers
• body (string, optional) — Request body

Spend caps (maxPerTx, maxDaily, maxMonthly, allowedDomains) are set on the agent at provisioning time and enforced server-side by ArisPay. There is no client-side budget parameter — attempts that exceed the delegation return a PaymentRejectedError.

Example prompt: "Use pay_api to fetch https://api.example.com/premium-data"

check_wallet

Report the configured agent, and — if PAYAGENT_WALLET is set — the on-chain USDC balance on Base.

Parameters: None

Example prompt: "Check my agent wallet"

Full delegation limits and spend history live at payagent.arispay.app.

How It Works

1. Agent calls pay_api with a URL.
2. If the server returns HTTP 402, payagent asks ArisPay to sign via CDP.
3. ArisPay validates the request against the agent's delegation limits and signs.
4. payagent retries with the signed X-PAYMENT header; the seller's facilitator settles on-chain.

No private key lives in this process. The signing key is held by Coinbase CDP; ArisPay enforces limits before signing. If a payment breaches the delegation, it's rejected before any on-chain action.

Install

npm install @arispay/payagent-mcp

Or invoke directly via npx @arispay/payagent-mcp from an MCP client config — no pre-install required.

Related

• payagent — the SDK for programmatic use
• x402 protocol — HTTP 402 payment standard

License

MIT