UCP Checker

add-to-cart

Add a product to cart on any UCP-enabled Shopify store and get a checkout URL. Requires a variant ID from the search-catalog or get-product-details results. Returns the cart contents, checkout URL, and a cart_id token. To build multi-item carts: pass the returned cart_id back on subsequent calls. The agent holds the cart_id — no server-side session needed. Example: domain: "allbirds.com", variantId: "gid://shopify/ProductVariant/12345" Multi-item: domain: "allbirds.com", variantId: "...", cartId: "gid://shopify/Cart/abc123"

Schema

Input Schema

{
    "type": "object",
    "required": [
        "domain",
        "variantId"
    ],
    "properties": {
        "cartId": {
            "type": "string",
            "description": "Cart token from a previous add-to-cart call. Pass this to add more items to an existing cart instead of creating a new one."
        },
        "domain": {
            "type": "string",
            "description": "The store domain (e.g., \"allbirds.com\")"
        },
        "country": {
            "type": "string",
            "description": "ISO country code for localized pricing/checkout (e.g., \"US\", \"GB\", \"CA\"). Optional."
        },
        "quantity": {
            "type": "integer",
            "description": "Quantity to add (default: 1)"
        },
        "variantId": {
            "type": "string",
            "description": "The product variant ID from search-catalog results (e.g., \"gid://shopify/ProductVariant/12345\")"
        }
    }
}
Verified Stores
3
Member Stores

Stores exposing the add-to-cart tool

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Weekly UCP Report
Issue #50 · Sep 14, 2026
+664
new verified stores
Verified rate
Latest spec
Cart capability