Same topic, related formats. Practice these next.
ReAct interleaves reasoning with tool calls, so each Observation injects a real result that grounds the next Thought, instead of the model continuing from its own guesses.
Imagine solving a treasure hunt. Pure chain-of-thought is like writing the whole plan from your armchair: you guess what is behind each door, then guess what is behind the next, building a long story entirely from memory. If one early guess is wrong, every step after it is built on that mistake. ReAct is like actually walking to each door and opening it before deciding where to go next. You think, then you check what is really there, then you think again using what you just saw. Because you keep looking at the real world between steps, a wrong guess gets corrected fast instead of snowballing. The thinking and the checking take turns, and each new thought stands on something you actually observed.
Everything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example. Click to expand.
Everything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example.
Everything important, quickly.
Name the mechanism first: grounding through interleaving. Then explain why the order matters, contrast open loop chain-of-thought with closed loop ReAct on a long task, show how drift compounds without Observations, and close with the cost, latency, and context management tradeoffs that ReAct introduces.
Real products, models, and research that use this idea.
What an interviewer would ask next. Try answering before peeking at the approach.
Red flags and common mistakes that signal junior thinking. Click to expand.
Saying ReAct just makes the reasoning longer or more detailed. The real win is grounding: each Observation is a real tool result, so the next Thought is anchored to data, not to the model's own continuation.
The night-before-the-interview bullets. Scan these on the way to the call.
Primary sources. Skim if you want the original framing.