Storefront MCP cart tools are being deprecated in favour of UCP Cart MCP

What’s changing 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.