acp-checkout-mcp

ACP Checkout — MCP Binding

Before writing code

Fetch live docs:

1. Web-search acp agentic commerce protocol MCP server implementation for MCP binding guidance
2. Fetch https://developers.openai.com/commerce/specs/checkout/ for checkout operation semantics
3. Web-search site:github.com agentic-commerce-protocol MCP for any official MCP examples
4. Fetch MCP SDK docs: web-search site:github.com modelcontextprotocol python-sdk or typescript-sdk for current SDK

Conceptual Architecture

What MCP Binding Means

ACP's REST checkout operations can be exposed as MCP tools via an MCP server. This allows AI agents that use tool-calling (Claude, ChatGPT, Gemini) to invoke checkout operations directly as tools rather than making raw HTTP calls.

Mapping REST to MCP Tools

Each REST checkout operation becomes an MCP tool:

REST Operation	MCP Tool Name	Description
POST /checkout_sessions	create_checkout_session	Create a new checkout session with items
POST /checkout_sessions/{id}	update_checkout_session	Update session (items, address, fulfillment)
GET /checkout_sessions/{id}	get_checkout_session	Retrieve current session state
POST /checkout_sessions/{id}/complete	complete_checkout_session	Submit payment to finalize
POST /checkout_sessions/{id}/cancel	cancel_checkout_session	Cancel the session

Tool Input Schemas

Each MCP tool accepts JSON input matching the corresponding REST request body. The tool's inputSchema should be derived from the ACP OpenAPI spec's request schemas.

Tool Output

Each tool returns the CheckoutSession object (or error) as JSON, matching the REST response body.

MCP Server Architecture

AI Agent (Claude/ChatGPT)
    ↓ tool call (JSON-RPC)
MCP Server (your code)
    ↓ business logic
Checkout Service (same logic as REST)
    ↓ payment
PSP (Stripe)

The MCP server wraps the same business logic that the REST endpoints use. The checkout service layer should be shared between REST and MCP bindings.