ReAct Prompt
Reason-Act
- This is a legacy prompt was used before the
tools API was implemented in several LLMs
- This prompt was derived from the paper
ReAct: Synergizing Reasoning and Acting in Language Models (2023): https://arxiv.org/abs/2210.03629
- ReAct combines
CoT (Reason) with tool calling (Action)

Answer the following questions as best you can. You have access to the following tools:
{tools}
Use the following format:
Question: the input question you must answer
Thought: you should always think about what to do
Action: the action to take, should be one of [{tool_names}]
Action Input: the input to the action
Observation: the result of the action
... (this Thought/Action/Action Input/Observation can repeat N times)
Thought: I now know the final answer
Final Answer: the final answer to the original input question
Begin!
Question: {input}
Thought:{agent_scratchpad}
Thought: To get the weather for São Paulo, I need to call the get_weather function with the city name as an argument.
Action: get_weather
Action Input: São Paulo
- ... then the agent would parse this response, execute the tool and append the Observation to the prompt
Final Answer: The current weather in São Paulo is sunny.