microsoft--agent-lightning/examples/calc_x/tests/test_mcp_calculator.py

# Copyright (c) Microsoft. All rights reserved.

import asyncio
import json
import os

import openai
from mcp import ClientSession
from mcp.client.stdio import StdioServerParameters, stdio_client


async def main():
    # 1. Initialize OpenAI client
    client = openai.OpenAI(
        base_url=os.environ["OPENAI_API_BASE"],
        api_key=os.environ["OPENAI_API_KEY"],
    )

    # 2. Prepare MCP stdio connection to the calculator server
    server_params = StdioServerParameters(
        command="uvx",
        args=["mcp-server-calculator"],
    )

    # 3. Ask the LLM to calculate an expression via a function call
    chat_resp = client.chat.completions.create(
        model="gpt-4.1-nano",
        messages=[{"role": "user", "content": "What is 31415926 * 11415789?"}],
        tools=[
            {
                "type": "function",
                "function": {
                    "name": "calculate",
                    "description": "Evaluate a mathematical expression",
                    "parameters": {
                        "type": "object",
                        "properties": {"expression": {"type": "string", "description": "The expression to calculate"}},
                        "required": ["expression"],
                    },
                },
            }
        ],
    )
    print(chat_resp)

    # 4. Extract the expression argument
    func_call = chat_resp.choices[0].message.tool_calls[0]  # type: ignore
    expr = json.loads(func_call.function.arguments)["expression"]  # type: ignore

    # 5. Connect to the MCP server and invoke the 'calculate' tool
    async with stdio_client(server_params) as (read, write):
        async with ClientSession(read, write) as session:
            await session.initialize()
            print("Session initialized.")
            result = await session.call_tool("calculate", arguments={"expression": expr})
            # The structured result is under `.structuredContent`
            value = result.structuredContent["result"]  # type: ignore

    # 6. Print out the result
    print(f"{expr} = {value}")


if __name__ == "__main__":
    asyncio.run(main())