Modules and agents
What you install decides what an assistant can ask.
Agent access turns the site into an MCP server, and its tools are derived from the modules already there rather than from a list somebody maintains.
Install the catalogue and the next build exposes a search tool and an item tool. Install booking and it exposes availability and a booking. Remove one and its tools go with it, so an assistant is never offered a door that leads nowhere. On a site with every tool-bearing module installed that is 13 tools, and on a site with none of them it is one: the tool that says what the site is.
The same rule holds for the discovery cards the site publishes, which are generated from that registry and therefore cannot describe a tool the site does not have. All of it stays off until agent access is switched on.
Which module gives which tool