Storefront MCP cart tools are being deprecated in favour of UCP Cart MCP
Shopify developer change
MerchantDiff detected this entry in Shopify's official developer changelog on June 24, 2026.
This Shopify update is categorized as Action Required, API, Deprecation announcement.
What changed
The cart tools on the Storefront MCP server are being deprecated in favour of the UCP-conforming Cart MCP tools: get_cart and update_cart on https://{shop}.myshopify.com/api/mcp are deprecated. Cart MCP implements the UCP cart capability (dev.ucp.shopping.cart, version 2026-04-08) and exposes the following tools at the https://{shop-domain}/api/ucp/mcp endpoint: create_cart: Create a new cart with line items and optional buyer context. get_cart: Retrieve the current state of a cart. update_cart: Replace the cart's contents. cancel_cart: Cancel a cart.
Who is affected
Apps and storefronts using the affected Storefront API surface should review this change.
What action may be needed
If you're building with the Storefront MCP cart tools: Migrate get_cart and update_cart calls to the Cart MCP tools, and update endpoints to use https://{shop-domain}/api/ucp/mcp. Include a meta object carrying ucp-agent.profile in every request, and a meta["idempotency-key"] (UUID) for cancel_cart. Note that update_cart uses PUT semantics: each request replaces the cart's full state, so send the complete line_items array on every update rather than patching individual fields.
Use the official Shopify entry below as the source of truth for technical implementation details, affected APIs, migration instructions and deadlines.
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