Detailed Explanation and Insights on the ReAct Framework

ReAct Prompt

Posted by LuochuanAD on February 11, 2026 本文总阅读量

Background

Various papers propose multiple reasoning frameworks for intelligent agents (also called frameworks): CoT, ToT, LLM+P, etc. Among them, the ReAct framework is used as the reasoning engine by several AI application development tools such as LangChain and LlamaIndex.

ReAct Framework

ReAct: Synergizing Reasoning and Acting in Language Models

PromptTemplate(
	input_variables = ['agent_scratchpad', 'input', 'tool_name', 'tools'],
	template = 'Answer the folllowing questions as best you can.
		You have access to the folowing tools: \n\n{tools}\n\n
		Use the following format: \n\n
		Question: the input question you must answer \n
		Thought: you should always think about what to do \n
		Action: the action to take, should be one of [{tool_names}] \n
		Action input: the input to the action \n...\n
		Observation: the result of the action \n...\n
		(this Thought/ Action/ Action Input/ Observation can repeat 3 times) \n
		Thought: I now know the final answer \n
		Final Answer: the final answer to the original input questions \n\n Begain! \n\n
		Questions: {input} \n
		Thought: {agent_scratchpad}'
)

During instantiation, this prompt guides a large language model to answer questions in a specific format that includes Thought, Action, Action Input, and Observation. This cycle may repeat up to 3 times as needed to arrive at the final answer.

References

LangChain official site: hwchase17/react