Code
T7021 not-for-a-chat
A screen that is offered to MCP reads or calls a function that is not offered to MCP. An error of the check. It is also the warning of what such a screen holds that a frame of another site cannot have.
Details
A chat app shows a screen that states offer: ['mcp'] in a frame of its own. There the screen reaches the app through the chat app: every read, useCall and Form is a call of the function's tool, so a function that is not offered to MCP has no tool, and the frame is answered code.T0001.
The warnings are of what works on a page of the app and not in a frame of another site:
| What | In the frame |
|---|---|
| A state kept in the device or in the browser | Starts at its default |
A script that unlock lists | Not loaded |
A member of an agent, or working of a flow or of an action | No tool: it works only where the chat app lets the frame connect, and is nothing elsewhere |
A function that a view hands to useQuery or useCall by a name worked out while running is not seen by the check.
The fix
Offer the function to MCP too, with offer: ['mcp'], or keep the screen for the app alone. For a warning, keep the state in the page or in the address, and draw what the frame cannot have only on the app's own pages.