- Checkout MCP and Cart MCP now include a buyer.consent object when the dev.ucp.shopping.buyer_consent extension (UCP 2026-08-25) is negotiated.
- Agents must declare the extension, display consent options from buyer.consent, and send the buyer’s choices on cart/checkout create, update, or complete calls; missing data triggers a warning that must be resolved before completion.
- Supports Shopify consent purposes (analytics, preferences, sale_or_sharing, marketing) and defaults to opt‑out when consent isn’t provided.