Expanding a bit on responses API.
The responses API from Open AI supports state-fullness, search, computer use and file search. This API is a bit slower than the conversation API, but allows end users to tap in to the OpenAI implemented search.
Google support a similar scheme with Gemini models (see search grounding)
Discourse AI from very early days opted to be as API agnostic as possible, so we implemented a first class tool and custom tool system.
You can see the full list of built in tools at: discourse-ai/lib/personas/tools at main · discourse/discourse-ai · GitHub
One of the tools we support is Google (search). It leans on the official Google search API to retrieve results.
This allows you to do stuff such as this: Exploring Gemini 2.5 Pro: AI Advancements - AI Conversation - Discourse Meta