MCP Explained: The Model Context Protocol in Agentic Commerce

MCP, the Model Context Protocol, is Anthropic’s open standard for connecting AI applications to external tools and data, often described as a USB-C port for AI. It is not a commerce protocol at all. In agentic commerce its job is narrow and foundational: it is the discovery layer, the standard way an agent finds a merchant’s tools before any commerce protocol runs. It became foundational enough that Anthropic donated it to a new foundation in December 2025 to keep it neutral.

Its role in commerce

A merchant or payment provider can expose its capabilities as MCP tools, and an agent can then find and call them the same way it discovers any other tool. This is why the commerce protocols treat MCP as plumbing they plug into rather than a competitor: ACP describes itself as MCP-compatible, and UCP lists MCP as one of its supported transports. Discovery has to happen before checkout, and MCP is the layer that handles it.

MCP in payments today

You can already see MCP used directly in payments. PayPal released what it called the industry’s first remote MCP server in April 2025, initially for conversational invoicing, and Stripe ships an MCP server that exposes payment operations as agent tools. Importantly, there is no first-party “MCP commerce extension” from Anthropic. Commerce use of MCP happens through third parties building MCP servers and through other protocols choosing MCP as a transport, not through a dedicated commerce spec.

Agentic Commerce Atlas runs its own MCP server, so you can query this reference live from an AI agent. See the MCP server, and if you want to build one, how to build a remote MCP server.

How to hold it in your head

The simplest way to keep MCP straight from the commerce protocols: MCP is a discovery protocol, not a commerce one. It sits underneath everything, the standard way an agent finds the merchant’s tools, while ACP and UCP define how the shopping and checkout actually run. They are complementary, and a single transaction can easily involve both. For where MCP sits among the other standards, see the protocol stack.

FAQ

Is MCP a commerce protocol? No. MCP is Anthropic’s general tool-and-data standard. In commerce it acts as the discovery layer, and the commerce protocols can use it as a transport.

How does it relate to ACP and UCP? It is plumbing they plug into. ACP is MCP-compatible and UCP supports MCP as a transport. MCP handles discovery; the commerce protocols run the purchase on top.

Is there an official MCP commerce extension? No. Commerce use happens through third-party MCP servers (PayPal, Stripe) and through other protocols using MCP as a transport, not a dedicated commerce spec.