Shopify’s own description of the tool that submits a checkout is “Submit checkout after buyer confirmation”, and nothing below says an agent can buy without the buyer. The changelog entry states that no merchant configuration is required, and it does not describe an opt-out either way — so nothing below claims merchants cannot opt out. The entry names no agent, browser or vendor, so none is named below , and it says nothing about fraud, chargebacks or liability, so neither does this piece in either direction. What Happened On September 28, 2026, Shopify’s developer changelog published an entry titled “WebMCP support for checkout. ” It describes four tools —navigate_to_storefront,get_checkout,update_checkout, andcomplete_checkout— that, in the entry’s own words, “let agents interact with the active checkout in the buyer’s browser session.