Agents

langgraph-prebuilt provides an implementation of a tool-calling ReAct-style agent - create_react_agent:

pip install langchain-anthropic

from langchain_anthropic import ChatAnthropic
from langgraph.prebuilt import create_react_agent

# Define the tools for the agent to use
def search(query: str):
    """Call to surf the web."""
    # This is a placeholder, but don't tell the LLM that...
    if "sf" in query.lower() or "san francisco" in query.lower():
        return "It's 60 degrees and foggy."
    return "It's 90 degrees and sunny."

tools = [search]
model = ChatAnthropic(model="claude-3-7-sonnet-latest")

app = create_react_agent(model, tools)
# run the agent
app.invoke(
    {"messages": [{"role": "user", "content": "what is the weather in sf"}]},
)