UCP vs ACP vs MCP
Not sure which protocol you need? See how UCP, ACP, and MCP compare across features, use cases, and compatibility.
Universal Commerce Protocol, Agent Communication Protocol, and Model Context Protocol — side by side.
UCP
Universal Commerce Protocol
The open standard for agentic commerce. Lets AI agents discover merchants, browse catalogs, execute checkouts, and manage orders — without custom integrations.
ACP
Agent Communication Protocol
A protocol for agent-to-agent communication. Defines how autonomous agents send structured messages to each other, regardless of the underlying AI model.
MCP
Model Context Protocol
Anthropic's protocol for giving LLMs structured access to tools, data sources, and APIs. Widely adopted by Claude, Cursor, and other AI coding tools.
| Feature | UCP | ACP | MCP |
|---|---|---|---|
| Purpose | |||
Primary use case What the protocol is designed for | ✓ Yes | ~ Partial | ✗ No |
E-commerce / checkout Native support for cart, checkout, payment flows | ✓ Yes | ✗ No | ✗ No |
Agent communication Protocol defines how agents send messages to each other | ~ Partial | ✓ Yes | ✗ No |
LLM tool/context access Provides structured tool/resource access for LLMs | ✗ No | ~ Partial | ✓ Yes |
| Governance | |||
Open specification Publicly documented, open-source spec | ✓ Yes | ✓ Yes | ✓ Yes |
Industry consortium Backed by multiple major companies | ✓ Yes | ~ Partial | ✗ No |
Open source reference impl. Reference SDK/library available | ✓ Yes | ✓ Yes | ✓ Yes |
| Technical | |||
Transport Primary communication transport | ✓ Yes | ~ Partial | ✓ Yes |
Discovery endpoint Standardised discovery via /.well-known/ or similar | ✓ Yes | ~ Partial | ~ Partial |
Auth / identity Standardised authentication mechanism | ✓ Yes | ~ Partial | ~ Partial |
Structured data format Well-defined message/payload schema | ✓ Yes | ✓ Yes | ✓ Yes |
Streaming support Real-time / streaming responses | ~ Partial | ✓ Yes | ✓ Yes |
| Commerce | |||
Cart & line items Protocol-level cart/line item management | ✓ Yes | ✗ No | ✗ No |
Payment processing Native payment mandate / payment flow | ✓ Yes | ✗ No | ✗ No |
Order management Track, cancel, return orders | ✓ Yes | ✗ No | ✗ No |
Product / catalog access Structured product search and browsing | ✓ Yes | ✗ No | ~ Partial |
| Ecosystem | |||
Launched Launch / GA date | ✓ Yes | ✓ Yes | ✓ Yes |
Adoption maturity Current level of real-world adoption | ~ Partial | ~ Partial | ✓ Yes |
Works alongside other protocols Can complement or interoperate with other protocols | ✓ Yes | ✓ Yes | ✓ Yes |
TL;DR — which one do you need?
Use UCP if…
- You're a merchant selling products
- You want AI agents to buy from your store
- You need standardised checkout & payments
- You're building an AI shopping agent
Use ACP if…
- You're building multi-agent workflows
- Agents need to delegate tasks to each other
- You want agent discovery and messaging
- Your system has many specialised agents
Use MCP if…
- You want to extend an LLM with tools
- You're building Cursor/Claude plugins
- You need to expose APIs to AI assistants
- You want RAG-style data source access
These protocols are complementary. A fully agentic commerce app might use MCP for LLM tool access, ACP for agent coordination, and UCP for the actual checkout flow.