Shopify's agent-commerce category filter didn't filter on any of 190 stores (shelfglance.com)

Shopify's recent analysis revealed a significant flaw in its agent-commerce category filter, which fails to function correctly across 190 tested stores. Although advertised as a part of the Universal Commerce Protocol (UCP) implemented in 2026, none of the stores were able to narrow their product search by category, regardless of the validity of the category provided. Instead, the experiment demonstrated that the filter either ignored requests entirely or returned an unfiltered set of products, indicating that the expected performance of the filter does not match its documented capabilities. This oversight is noteworthy for the AI/ML community as it highlights the importance of rigorous testing of API endpoints rather than solely relying on their schema documentation. The findings suggest that while Shopify's architecture aims to streamline interactions for AI shopping agents, its current implementation fails to facilitate effective catalog searches by category. As the UCP continues to evolve, this scenario underscores the need for ongoing scrutiny and validation of protocol behaviors to ensure they align with intended functionalities. The study, conducted by Shelfglance, emphasizes that merchants may be unknowingly disadvantaged by category fields in their product listings that don't operate as expected.