It’s done by software using an LLM, not just a raw LLM. They do only work with text, but you can get it to output the text “get_weather(mylocation)”, and instead of just outputting that directly to the user, the software running on top of the LLM runs a " get_weather" function that calls some weather API. The result of that function is then output to the user.

Any time you see an “AI” taking “actions”, this is what happens in the background for every action.

I find Qwen3.5 is the best at toolcalling and agent use, otherwise Gemma4 is a very solid all-rounder and it should be the first you try. Tbh gpt-oss is still good to this day, are you running into any problems w it?