basic_tool_node.py

import json
from typing import Any
from langchain_core.messages import ToolMessage

# Create a function to run the tools
class BasicToolNode():
    """A node that runs the tools requested in the last AIMessage."""
    def __init__(self, tools: list) -> None:
        self.tools_by_name = {tool.name: tool for tool in tools}

    def __call__(self, state: Any) -> dict[str, Any]:
        if messages := state.get("messages", []):
            message = messages[-1]
        else:
            raise ValueError("No messages found in state")
        outputs = []
        for tool_call in message.tool_calls:
            tool_result = self.tools_by_name[tool_call["name"]].invoke(
                tool_call["args"]
            )
            outputs.append(
                ToolMessage(
                    content=json.dumps(tool_result),
                    name=tool_call["name"],
                    tool_call_id=tool_call["id"],
                )
            )
        return {"messages": outputs}