UCP Cart Capability
LiveVerifiedNew optional UCP spec capability (March 2026) enabling AI agents to add multiple items to a shopping cart at once from a single store, matching how human shoppers behave.
The UCP Cart capability is a new optional specification addition announced by Google on March 19, 2026. It enables AI shopping agents to save or add multiple items to a shopping cart simultaneously from a single store, replicating the natural behavior of human shoppers who add multiple items before checkout.
Prior to this capability, UCP interactions were focused on single-item checkout flows. The Cart capability is optional and merchants can choose whether to implement it, giving them flexibility in how deeply they support agentic shopping.
Why This Matters for UCP
The Cart capability extends UCP beyond single-item checkout to support multi-item shopping sessions, making agentic commerce feel natural and efficient for shoppers.
UCP Capabilities
UCP Endpoint
Live — Endpoint not yet publicly available
Integration Example
// UCP Cart capability - add multiple items at once
const cart = await ucpClient.cart.create({
merchant_id: 'merch_123',
items: [
{ product_id: 'prod_abc', quantity: 2, variant_id: 'var_blue_m' },
{ product_id: 'prod_xyz', quantity: 1, variant_id: 'var_default' }
],
shopper_token: identityToken // optional: identity-linking
});
// Returns a cart_id usable in subsequent checkout flowCategory
Developer ToolsUCP Status
LiveTags
Pricing
free
Related Guides
Reviews
★★★★★4.6 (5 reviews)These are illustrative examples to show what reviews will look like. Submit your own experience below.
Y. Okonkwo
API Engineer · Feb 25, 2026
Good tool for UCP conformance testing. Runs fast and the output is easy to parse in CI. Would like a JSON output mode — currently only text.
B. Thompson
Staff Engineer · Mar 5, 2026
This saved us days of work. Dropped it into our pipeline and had UCP endpoint validation running in about 20 minutes. Documentation is accurate.
K. Park
Backend Developer · Feb 18, 2026
The best developer tool in this category. TypeScript types are correct and complete. Error messages actually tell you what went wrong.
E. Garcia
Senior Engineer · Jan 30, 2026
Solid tool. The test suite coverage is excellent. I found one edge case in the payment token validation that the maintainers fixed within 48 hours.
M. Fischer
DevTools Engineer · Mar 8, 2026
Integrated in an afternoon. The discovery endpoint just worked. The CLI flags are well-designed — composable, no magic defaults.
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