Prerequisites: Basic working knowledge of MCP Client/Server communication
I asked my vacation planner agent for the best flight to Aruba. Its comparisons kept degrading. Some of it was my context. Some of it was data the sellers never sent. This talk is about the second part. The CA$587 fare hid a bag costing up to CA$390, US dollar pricing at my card’s FX rate, and sellers whose bag fees even Google’s Flight aggregator could not see.
ChatGPT Plugins, Claude Marketplace, and personal agents like OpenClaw and Hermes now call your Shop, Search, Filter, and Sort APIs as tools. Whoever runs the agent owns the model, the memory, and the sandbox. When your API becomes an MCP tool inside someone else’s agent, your schema has to carry every promise your website used to make.
Agents don’t write bad reviews: if your storefront makes them crawl, scrape, and screenshot, they quietly take their customer to a store that answers in schema, and you never see the sale you lost.
Three shifts:
- Page to payload: fees, currency, fare classes, and Sponsored labels must travel in the tool response.
- Disclosure survival: whether those promises survive the model’s paraphrase.
- The Ranking Receipt: a machine readable record of what was paid for, what was weighed, and why the agent chose a rival over you.