Awareness of available retrievers

[PascalNobereit]

Hi!

We are building Retrieval Augmented Generation systems for government institutions.

We use a variety of data sources which leads to each requiring tailored retrievers.

People often just ask the system (mostly chatbots) stuff like "I'm looking for an event this evening, can you lookup events?" -
which will trigger a self query retrieval accessing our vector db.

If this specific lookup returns no results, the top level llm (the generator) will not be augmented with any events, and therefore say it can't lookup events, which is wrong, because its just that the specific query did not return any results.

Now the question is: what is the best option to make the generator aware of it's options, that is, which retrievers is has access to?
Should we just pass a sentence about each into the system prompt or rather specify the retrievers as function using OpenAI function calling?