Payment Agent Demo

Agentic Commerce demo with Stripe and Visa TAP (Trusted Agent Protocol)

Agentic Commerce Flow

[ AI Agent (e.g. Claude) ]
            │
            │ 1. Connects to remote MCP server with auth token and wallet id
            ▼
[ Remote MCP Server (Wallet Provider) ] 
            │
            │ 2. Makes checkout tool available to Agent. Holds the agent's private key. 
            | 3. Private key is used to sign payload to create Visa TAP signature
            ▼
 [ Merchant Storefront API ]
            │
            │ 4. Validates the signature with agent's public key fetched from Visa agent registry.
            │ 5. Verifies that the item is in stock and the price is correct.
            ▼
     [ Stripe API ] 
            │
            │ 6. Storefront triggers stripe.PaymentIntent.create()
            ▼
 [ Customer's Bank Account ] <-- Funds are safely moved

Integration Flow

 ┌──────────────────────────────┐
 │    MERCHANT STOREFRONT       │
 └──────────────┬───────────────┘
                │
                │ 1. Publishes OpenAPI Spec / Documentation. 
                |    RFC 9421 does not specify the data schema of the CheckoutRequest. 
                |    Therefore, the Agent / MCP server must follow the merchant storefront's spec or signature validation will fail.
                ▼
 ┌───────────────────────────────────────────────────────┐
 │    WALLET PROVIDER                                    │
 ├───────────────────────────────────────────────────────┤
 │  • Provides tools and holds agent's private key       │
 │  • Configures MCP Tool parameters to match.           |
 │  • Signs payload using their private key.             |
 └───────────────────────────────────────────────────────┘

Project Structure

project-root/
├── .venv/                          <-- single, unified virtual environment
├── pyproject.toml                  <-- Holds all Python dependencies for all 3 components
├── client-bridge/
|   ├── .mcp_access_token           <-- File where the Agent's access token will be stored
|   └── client.py                   <-- Bridge to allow Claude to access remote MCP server with authentication
|
├── wallet_provider/                <-- Remote MCP server to allow an agent (like Claude) to make payments
│   ├── create_tap_sig.py
|   ├── generate_test_keys.py       <-- generate a public/private key pair for the agent
│   └── main.py
|
└── merchant_api/                   <-- simulates merchant store API which allows agents
    ├── mock_visa_directory.py  
    └── server.py

Quick Start Guide

1. Add MCP Server to Claude desktop config

"mcpServers": {
    "agent-stripe-checkout": {
      "command": "uv", 
      "args": [
        "run",
        "--directory",
        "/Users/<your_user>/<path_you_cloned_to>/payment-agent-demo/payment_mcp",
        "main.py"
      ],
      "env": {
        "DEMO_AGENT_WALLET_ID": "mock_visa_tap_agent_01"
      }
    },
}

2. Run Merchant Storefront API

cd merchant_api/
uv sync

Run the merchant API server: uvicorn server:app --reload

Requirements

• Python >= 3.14
• uv (Astral)

Environment variables

Run generate_test_keys.py to get create a private/public key pair for your agent

At minimum set the following values in the appropriate .env files:

• STRIPE_SECRET_KEY — your Stripe test secret key (required by both components in this demo)
• DEMO_AGENT_WALLET_ID — used by the MCP server when running in Claude/Desktop integrations