Agents And Tool Use easy
You are building a research agent that must look up facts it does not know and adjust its plan based on what it finds. Which loop structure fits?
- A One planning call that writes the full list of tool calls upfront, executed without review.
- B A ReAct loop that interleaves reasoning, a tool action, and an observation each step.
- C A single prompt that asks the model to answer from memory, skipping tools to save cost.
- D A fixed pipeline of the same three tool calls in the same order for every question.
Answer: B. A ReAct loop that interleaves reasoning, a tool action, and an observation each step.
**ReAct** lets each observation inform the next action, which is exactly what adaptive research needs, at the cost of one model call per step. Plan-then-execute (A) is cheaper and fine when steps are predictable, but it cannot react when a lookup returns something unexpected.
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