If your store runs a conversational AI agent on Shopify and that agent answers shipping, returns or warranty questions, check which endpoint it’s calling. Shopify’s legacy Storefront MCP cart tools sunset on August 31, 2026 — eleven days from this writing — and a merchant thread on Shopify’s own developer forum says the tool agents use to answer policy questions has no equivalent on the protocol replacing it.

What’s changing August 31

Shopify’s developer changelog, posted June 24, 2026, deprecates two tools on the legacy Storefront MCP server (https://{shop}.myshopify.com/api/mcp): get_cart and update_cart. They’re replaced by Cart MCP, which implements the Universal Commerce Protocol’s dev.ucp.shopping.cart capability (version 2026-04-08) at https://{shop-domain}/api/ucp/mcp with four tools: create_cart, get_cart, update_cart, cancel_cart.

The changelog is explicit that this is a deadline, not a suggestion: “The deprecated tools will be maintained until August 31, 2026, but all documentation will refer to the Cart MCP tools.” Migrating means more than swapping the URL. Per Shopify’s Cart MCP docs, every request needs a meta object carrying a ucp-agent.profile, cancel_cart calls need a meta["idempotency-key"] UUID, and update_cart switched to PUT semantics — each call replaces the cart’s entire line-item state rather than patching one field.

The gap a merchant found, not Shopify

The changelog only ever mentions cart tools. It says nothing about search_shop_policies_and_faqs — the Storefront MCP tool agents call to answer a shopper’s shipping, returns or warranty question before or during checkout.

A developer running conversational agents on eight Shopify storefronts posted what they found while migrating, in a forum thread titled “No UCP successor for search_shop_policies_and_faqs before the Aug 31 sunset”:

“The gap is search_shop_policies_and_faqs, which our agents rely on for shipping, returns and warranty questions. It is only exposed on /api/mcp, and that endpoint returns sunset: Mon, 31 Aug 2026 00:00:00 GMT on every response — including the tools/list that advertises the tool. We could not find an equivalent on /api/ucp/mcp: without a profile the server’s full set is 13 tools and none covers policies or FAQs.”

Catalog and cart migrated cleanly for this merchant — declaring the dev.ucp.shopping.catalog.search, catalog.lookup and dev.shopify.catalog capabilities on /api/ucp/mcp returns the 12 tools they need. The FAQ tool is the one piece with nowhere to go.

So is the whole endpoint sunsetting, or just cart?

The poster answered their own question a day later, after re-reading the changelog: “only the cart tools were deprecated, not the endpoint. The changelog states that get_cart and update_cart on /api/mcp are deprecated in favour of the UCP Cart MCP, and search_shop_policies_and_faqs is not mentioned anywhere in it.” Shopify’s own thread marked that reply the accepted answer.

That leaves a real discrepancy standing as of this writing: the documented deprecation covers cart tools only, but the HTTP Sunset header — an RFC 8594 signal meant to warn a whole resource is going away — is present on every response from /api/mcp, FAQ tool included. A merchant relying on the header would conclude the tool is dying; a merchant relying on the changelog would conclude it’s fine. Neither reading comes with a stated Shopify decision, and the thread has no reply from Shopify staff as of this writing.

What to check if you run an agent on a Shopify storefront

  • Split your tool calls by endpoint. If your agent calls get_cart or update_cart on /api/mcp, that stops being maintained August 31 — migrate to /api/ucp/mcp with the profile object, idempotency key and PUT semantics above.
  • If you depend on search_shop_policies_and_faqs, don’t assume it survives past August 31 just because the changelog doesn’t name it — the header on the endpoint it lives on says otherwise. Have a fallback ready: a structured llms.txt or well-linked policy pages give an agent a second way to find shipping and returns answers that doesn’t depend on this one MCP tool.
  • Budget the cart migration regardless of the FAQ question — the deadline for get_cart/update_cart is fixed and eleven days out from this article’s publish date.

FAQ

What happens to Shopify’s Storefront MCP cart tools on August 31, 2026?

get_cart and update_cart on the legacy /api/mcp endpoint stop being maintained. Shopify’s changelog directs developers to migrate to Cart MCP’s create_cart, get_cart, update_cart and cancel_cart tools at /api/ucp/mcp, which requires a ucp-agent.profile in the request metadata and uses PUT semantics for updates.

Does Shopify’s UCP Cart MCP replace search_shop_policies_and_faqs?

Not as of this writing. A merchant who migrated eight storefronts found no UCP-conformant tool that answers shipping, returns or warranty questions — without a declared profile, /api/ucp/mcp exposes 13 tools and none of them cover policies or FAQs, and Shopify’s changelog doesn’t mention the tool at all.

Is Shopify sunsetting the entire /api/mcp endpoint, not just cart tools?

It’s ambiguous. The changelog text only deprecates the cart tools, but every response from /api/mcp — including calls unrelated to cart — carries an HTTP Sunset: Mon, 31 Aug 2026 00:00:00 GMT header, which by convention signals the whole resource is going away. Shopify has not publicly reconciled the two as of this writing.

Sources

A migration deadline that quietly drops an agent-facing capability is exactly the kind of gap AgentReady’s scan is built to catch — not whether your store speaks the right protocol, but whether an agent can actually get a straight answer out of it.