Since 2026 every Shopify storefront answers an agent-commerce endpoint at POST /api/ucp/mcp, advertised atGET /. It speaks the Universal Commerce Protocol over JSON-RPC, and the tool that matters issearch_catalog: an AI shopping agent asks a store for its catalogue and gets structured product data back - integer prices in minor units with a currency, variants, SKUs, canonical URLs, and a Shopify taxonomy category per product. We were about to write a paragraph about what it costs a merchant to leave the category field blank. Method 200 stores, drawn deterministically from a corpus of 10,099 known Shopify storefronts: sort the hostnames, take every Nth. max = 1 return nothing - nothing costs a cent Calls 2 and 3 only mean something together.