Basically I have a use-case where I am building an llm-based tutor where some questions you ask the tutor can be adequately answered by gpt-4o-mini but others required gpt-4o. I'm looking for a router that can route to gpt-4o only when necessary and otherwise route to the cheaper gpt-4o-mini. First of all, is this even something that can be done reliably at this point? If so, are there any recommendations for LLM routers that can do this?