Protocol
Transport Protocols
How do stores expose their commerce APIs? Transports define the communication protocol between agents and merchants.
Transports are one of the four building blocks of the Universal Commerce Protocol. They define how agents communicate with stores — whether via direct HTTP calls, LLM tool invocation, agent-to-agent negotiation, or embedded interfaces. Each transport works with the same capabilities and tools, just over a different wire protocol.
Frequently Asked Questions
What transport protocols does UCP support?
UCP supports four transports: REST (standard HTTP APIs via OpenAPI), MCP (Model Context Protocol for LLM tool calling), A2A (Agent-to-Agent via Agent Cards), and Embedded (host-embedded interfaces via OpenRPC). Stores can support multiple transports simultaneously.
Which transport is most common?
MCP is currently the most widely adopted transport, as it allows LLMs to directly invoke store operations as callable tools. REST is also common for traditional API integrations.
Can a store support multiple transports?
Yes. A store's UCP profile can declare multiple services, each using a different transport. For example, a store might offer both an MCP endpoint for AI agents and a REST API for traditional integrations.
Explore Protocol Data
Verticals
retail, lodging, travel & food by industry
Capabilities
which commerce features stores support
Vendors
capabilities & extensions by namespace authority
Tools
what MCP operations agents can invoke
Payment Handlers
which payment methods are accepted
Spec Versions
which protocol versions are in use
Weekly UCP Report
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Weekly UCP Report
Issue #53 · Oct 5, 2026
+664
new verified stores
Verified rate
Latest spec
Cart capability