LLMs are good at fuzzy pattern matching and data manipulation. The upstream comment comparing to awk is very apt. Instead of having to write a regex to match some condition you instruct an LLM and get more flexibility. This includes deciding what the next action to take is in the agent loop.

But there is no reason (and lots of downside) to leave anything to the LLM that’s not “fuzzy” and you could just write deterministically, thus the agent model.