I posted my issue to the wrong thread yesterday. I'm sorry I hogged that thread. I've just noticed what I did, so I deleted it.
The thing is, my agent says it doesn't have access to the dataset. I created query_engine_tools, and when I iterate over them with a query, I get correct answers about the dataset. However, when I use them for an agent, LLM says it doesn't have access to the dataset. I've been trying to fix my code for 2 days and I'm out of ideas. I hope someone had this same problem and found a solution, because I haven't found it anywhere.