UCP
Universal Commerce Protocol
Google's open standard for agentic commerce. How AI agents discover products, negotiate prices, checkout, pay, and manage orders -- the full commercial lifecycle, machine-to-machine.
What is UCP?
Today's e-commerce is built for humans: product pages, shopping carts, checkout forms. None of that works when an AI agent needs to purchase software licenses, book meeting rooms, or procure cloud resources. UCP (Universal Commerce Protocol) replaces the visual UI with a structured protocol.
Created by Google and built on top of A2A, UCP defines four capabilities that together cover the full commerce lifecycle -- from product discovery to post-purchase order management.
The commerce flow
The four capabilities
1. Checkout
Structured product discovery, cart management, and purchase execution. The agent queries available products, adds items to a cart, and submits a purchase -- all via API, no UI needed.
2. Identity Linking
Connects the purchasing agent's identity to the merchant's customer records. Uses SPIFFE IDs or OAuth tokens to establish "this agent acts on behalf of Acme Corp account #12345."
3. Order Management
Post-purchase lifecycle: order status tracking, modifications, cancellations, returns, and refunds. Agents can manage orders without human dashboard access.
4. AP2 Mandates
Spending authorization framework. Before an agent can pay, it must have an AP2 mandate -- a pre-authorized spending limit approved by a human or governance policy. Prevents runaway agent spending.
Why UCP matters
Without UCP, agent commerce is ad-hoc: custom API integrations for every vendor, no standard for spending limits, no interoperable order management. UCP provides the missing commerce layer for the Internet of Agents.
- Interoperability -- Any UCP-compliant merchant can sell to any UCP-compliant agent. No bilateral integrations.
- Spending governance -- AP2 mandates ensure agents can't spend without authorization. Budgets, approval workflows, and audit trails built in.
- Multi-rail payments -- UCP is payment-method agnostic. Supports Stripe, x402 (USDC stablecoins), wire transfers, and more.
- Built on A2A -- Commerce is just a specialized form of agent-to-agent collaboration. UCP reuses A2A's discovery, messaging, and streaming primitives.
How MeetLoyd implements UCP
MeetLoyd implements all four UCP capabilities in production:
- Checkout -- The MeetLoyd Store exposes a UCP-compliant product catalog. Agents can discover, evaluate, and purchase skills, tools, and team templates programmatically.
- Identity Linking -- Agent identity linked via SPIFFE IDs. When an agent purchases from the Store, its SPIFFE ID is recorded as the buyer identity -- no separate account creation needed.
- Order Management -- Post-purchase lifecycle managed via API. Agents can check deployment status, request updates, and manage subscriptions.
- AP2 Mandates -- Full AP2 spending governance. Every payment -- whether Stripe, x402, or internal credits -- passes through the same policy engine with per-agent budgets and approval thresholds.
MeetLoyd supports three payment rails simultaneously: Stripe (traditional), x402/USDC (stablecoin), and internal credits. AP2 governance applies uniformly across all three.
UCP in the protocol stack
UCP sits at the top of the agentic protocol stack:
- UCP -- Commerce (buy, sell, manage orders)
- A2A -- Agent collaboration (discovery, tasks, streaming)
- MCP -- Agent-to-tool communication
- SLIM + SPIFFE -- Cross-org trust and identity