The new ChatGPT 5.5 Instant broke multi-step App/MCP tool calls

My team and I are also noticing many issues that have surfaced with this model change, including:

  • Apps no longer remain in context, they need to be re-added for each query (also reported here).
  • If the app isn’t mentioned in a follow-up query ChatGPT defaults to a web search or its own knowledge.
  • Multi-turn conversations require more intentionality, which most users aren’t aware of.

A few screenshots demonstrating the problem:

Invoking IHG app to context (correctly calls app):

Follow up query in the same chat without re-invoking the app (makes a web search):

Same test with the Radisson app in a new conversation (all happening within a single chat):

Some extra notes:

  • This seems to work much better with the medium/high models even when apps aren’t re-added to context.
  • In previous versions of the interface the apps would remain in context until the user explicitly removed them, which felt like a much more expected UX.