"""计算工具"""
from langchain_core.tools import tool


@tool
def calculate(expression: str) -> str:
    """计算数学表达式，输入如 '2+3*4'"""
    try:
        result = eval(expression, {"__builtins__": {}}, {})
        return f"计算结果: {expression} = {result}"
    except Exception as e:
        return f"计算错误: {e}"


TOOLS = [calculate]