I don't think the answer to your cross-post on GenAI SE is correct. If the whole prompt is parsed by an LLM normally, then the following text that is generated is merely an approximation, a statistical likelihood, and not a guaranteed outcome. In other words, it's up to the LLM itself if it wants to respect your requirement. The LLM itself is, to the best of my knowledge, not designed to be able to do that, because it doesn't reason; it doesn't comply with strict rules, because the prompt isn't parsed to generate strict rules. It's read as tokens to generate new tokens.

In other words, the answer is "no" as long as there is no bypass for the prompt.

Would you like to comment on that? In case I'm wrong, I'd appreciate a correction.

Andreas demands justice for humanity‭ I think you're right (though still a useful answer if it works often enough, for some use cases). I've just checked the API too. OpenAI released a new API for web search in March 2025: https://platform.openai.com/docs/guides/tools-web-search. But it doesn't have any option yet to restrict the search to only certain domain(s).

Thanks. I decided to post an answer about that after receiving your confirmation and after reasoning a bit further about it. I'm not updated on the latest developments in LLMs, but I still haven't seen anything that's given me reason to reconsider my reservations against them. What that means, is that I wasn't comfortable posting an answer without refreshing and asserting my understanding of it.

Andreas demands justice for humanity‭ Thanks, this is difficult to stay up to date on LLM. E.g. the OpenAI search API just got released a month ago. This is one reason why I asked a few genAI questions.

That isn't as much of a concern. What I refer to, are the fundamentals of this form of generative AI. Addons and extensions don't change those bits; the design that incorporates certain attributes deep in the system. For example the hallucinations, or the inability to really reason. I'm unaware of any developments that have resolved these issues.

Andreas demands justice for humanity‭ The search API could've easily added domain restrictions.

It couldn't have influenced the training material.