What are ReAct agents and how do they work?

I used to think AI agents were more capable than people gave them credit for, until I hit a breaking point. The agent reasoned through a multi-step task, took actions, and delivered a confidently structured, completely wrong answer—because it never once checked its assumptions against real data. And there’s the rub: even an agent is still built on a raw LLM, which can fail by reasoning from bad assumptions rather than real data.