Frontier models from a year ago had issues with consistent tool calling, instruction following was pretty good but could still go off the rails from time to time.

Open weight models have those same issues. They are otherwise fine.

You can hook them up to a vector DB and build a RAG system. They can answer simple questions and converse back and forth. They have thinking modes that solve more complex problems.

They aren't going to discover new math theorems but they'll control a smart home and manage your calendar.