I have followed the guide here [image] Storefront MCP server Learn how to use the Storefront MCP server tools to help shoppers browse products, manage carts, and checkout from a specific Shopify store. but this tool doesn’t seem to be working. It only creates…

Hi @datvm23 Thanks for flagging this behaviour - digging into this on my side now.

Hi again @datvm23 We were unable to replicate this on our side - and it’s working when we try it out on a test store. Can you share a request ID (from the response headers) on their MCP update_cart tool request for us to dig deeper? It’s possible this is a product publication issue - where the prod…

Hi @Liam-Shopify , I am following this as well because I am running into the same issue as datvm23. Could you please confirm what would be the correct product setup and if possible an example of your working test API request? I’ve tried this on two separate stores with live products published on Sal…

Hey @Joel_Chan Do you have a requestID that we could use to see what might be going on here?

Hi @Liam-Shopify , Please see below for an example output from a request I made that created an empty cart using an active variant id with inventory in stock: "{"instructions":"Ask if the customer has found everything they need. If they’re ready to check out:\n\n1. First help them complete their ca…

Thanks for sharing this Joel - digging into this more on my side.

Still unable to see what might be happening here - are you still seeing this issue?

Hi I’ve the same problem. Same payload and no products in the cart. It’s always empty. The variant is available and in stock. As endpoint i use www.domainname.com/api/mcp as described here: Storefront MCP server

To Replicate the issue you can use the below code import json # Basic setup for Storefront MCP server requests store_domain = "shopchatmcp.myshopify.com" # 🔸 Replace with your store domain mcp_endpoint = f"https://{store_domain}/api/mcp" # Prepare the JSON-RPC payload for updating cart payload =…

Hey everyone, Vedant posted in a separate thread and I was able to identify the issue. See if the solution I provided here will work for you as well: [image] While creating Cart using update_cart from shopify MCP its giving the checkout url empty MCP & LLM Hey…

Storefront MCP tool update_cart failure

Agentic Commerce

KyleG-Shopify October 9, 2025, 9:52pm 11

Hey everyone, Vedant posted in a separate thread and I was able to identify the issue. See if the solution I provided here will work for you as well:

Topic		Replies	Views
While creating Cart using update_cart from shopify MCP its giving the checkout url empty Agentic Commerce	4	201	October 10, 2025
Storefront MCP tool update_cart does not update cart? Agentic Commerce	3	214	February 3, 2026
Feature request: Storefront MCP server update_cart tool should support line item attributes Agentic Commerce	2	88	January 14, 2026
After Aug 31, will the deprecated Storefront MCP cart tools stop responding, or just be unsupported? Agentic Commerce	1	41	August 27, 2026
Getting `invalid id` on `cartLinesUpdate` storefront mutation Hydrogen and Storefront APIs storefront-api	1	100	November 25, 2025

Storefront MCP tool update_cart failure

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