ai-agents-react-parser-stop-to-when-using-llama3-or-similar-llms-with-the-react-a-6f153ec1

THEN Set the LLM's stop token to 'Observation:' to ensure generation stops immediately after the Observation line and does not produce an extraneous Final Answer. Pass the 'stop' parameter when initializing the LLM (e.g., ChatOllama(model='llama3', stop=['Observation:'])). Then use create_react_agent with that LLM.

from langchain_community.chat_models import ChatOllama
llm = ChatOllama(model='llama3', stop=['Observation:'])
agent_runnable = create_react_agent(llm, tools, prompt)