AI news · Shopify Shop MCP · AI shopping agents
Three Claude models pick different products from one Shopify list
Given the same 20 products from Shopify’s catalogue, Haiku, Sonnet and Opus never agreed on the first choice across six searches.
Which store wins an order from an AI shopping agent can depend on the model underneath it. In an experiment published on 2 November 2026, optimisation consultant Slobodan Manić saved Shopify’s top 20 results for six everyday searches, from coffee beans to a yoga mat, and asked Claude Haiku 4.5, Sonnet 5 and Opus 5 to choose one product to buy for a shopper, 50 times per model per search; nothing was actually bought. No search ended with the three models agreeing on a favourite.
He pulled the lists through Shop MCP, which Shopify launched in October as a single connection that takes any agent from search to a finished Shop Pay checkout across more than a billion catalogue products, with no API key needed to search.
Each model was steady on its own. Haiku gave its favourite 67 per cent of its picks on average, Opus 89 per cent and Sonnet 94 per cent. Haiku and Sonnet tended to choose whichever item had the most reviews. That favoured a nobl water bottle that the catalogue credited with 447,221 reviews and a perfect score, while nobl’s own product page counted 6,537 when Manić checked. Opus described its choice as safe or safest in 222 of 300 answers.
Manić ran the models through Claude Code, which comes with Claude Pro at $20 a month on our 2 November check; he does not say which plan he used or how much usage the 1,980 picks took.
About half of Haiku’s and Sonnet’s picks went to the most-reviewed product, so the review count in Shopify’s catalogue, about 68 times the figure on nobl’s own product page in this case, is the number a merchant on Shop MCP has most reason to check.
Sources
- Search Engine Journal: 3 AI Models Shopped Shopify’s Catalog, Each Picked A Different Winner. Checked
- Shopify: Add shopping and Shop Pay checkout to any agent with Shop MCP. Checked
Alexandre S.
Alexandre S. is a creative ad strategist and copywriter with ten years' experience in digital marketing across multiple channels.
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