What is the Model Context Protocol (MCP)?
The Model Context Protocol (MCP) is an open-source protocol developed by Anthropic and published in November 2024. It defines a standardized interface for connecting AI agents (LLMs) to external data sources and tools: databases, APIs, file systems, business applications.
Concretely, MCP allows an AI agent to "plug in" a capability, for example, reading a user's Gmail emails, creating a task in Notion, or querying a SQL database, without the agent developer needing to write a proprietary integration for each service.
MCP is adopted by Claude (Anthropic), and many third-party integrations exist for Slack, GitHub, Google Drive, Stripe, and dozens of other services.
What is the Universal Commerce Protocol (UCP)?
The Universal Commerce Protocol (UCP) is a standard launched January 11, 2026 by Google and Shopify, with a coalition of retail and payment partners. It defines a standardized interface for the complete purchase journey: product discovery, inventory checking, checkout, payment via AP2, and post-purchase management.
Comparison table: UCP vs MCP
| Dimension | MCP (Anthropic) | UCP (Google/Shopify) |
|---|---|---|
| Created by | Anthropic (Nov. 2024) | Google + Shopify (Jan. 2026) |
| Main objective | Connect AI agents to tools and data | Standardize agentic commercial transactions |
| Application domain | Access to any data source/tool | E-commerce and retail only |
| Payment management | No (uses third-party APIs) | Yes (via integrated AP2) |
| Identity management | Partial (via MCP servers) | Yes (dedicated Identity Linking) |
| Transport | JSON-RPC via stdio or HTTP/SSE | REST + JSON-RPC |
| Open-source | Yes (github.com/modelcontextprotocol) | Yes (github.com/Universal-Commerce-Protocol/ucp) |
How MCP and UCP work together
In a real agentic commerce scenario, MCP and UCP operate in complementary layers. Example: an AI agent managing enterprise purchasing:
- MCP: agent connects via MCP to the company's ERP to read current stock levels
- MCP: agent accesses budget management tool via MCP to check available budget
- UCP: agent queries UCP-compatible supplier catalogs to compare offers
- UCP: agent initiates order via UCP checkout and payment via AP2
- MCP: agent updates ERP via MCP to reflect the placed order
MCP handles integrations with the company's internal systems; UCP handles transactions with external suppliers. Both protocols are active simultaneously in different layers.
Can an MCP server expose a UCP catalog?
Yes, and this is an interesting emerging architecture. A developer can create an MCP server that "wraps" a merchant's UCP endpoints, allowing an AI agent that supports MCP but not UCP natively to access that merchant's catalog and checkout via the MCP interface.
This approach is particularly useful during the transition phase where not all agents natively support UCP. "UCP bridge" MCP servers are starting to appear in the open-source community.
Which one to implement first?
If you're an e-commerce merchant, implement UCP as a priority. It's the protocol specifically designed for commerce and adopted by consumer AI agents for purchases.
If you're a tool or API publisher used by teams with AI agents, create an MCP server to expose your features to agents. MCP is the universal integration layer for non-commerce tools.