MCP Apps: ui/notifications/tool-result missing _meta in ChatGPT

ChatGPT Apps SDK
1

I’m migrating a ChatGPT app UI from the OpenAI bridge (window.openai) to the MCP Apps bridge (ui/* over postMessage).

In the OpenAI bridge, we relied on window.openai.toolResponseMetadata for UI-only data and it worked.

After moving to MCP Apps, we expect the same data to be available as top-level params._meta in ui/notifications/tool-result (per docs/spec), but it is missing in ChatGPT.
mcp apps spec

Expected

app.ontoolresult should receive:

  • params.content

  • params.structuredContent

  • params._meta (UI-only metadata)

Actual (ChatGPT host)

app.ontoolresult receives:

  • params.content :white_check_mark:

  • params.structuredContent :white_check_mark:

  • params._meta :cross_mark:

So the tool-result notification arrives, but top-level _meta does not appear to be forwarded.