claude-code-sdk-python/examples/mcp_calculator.py

#!/usr/bin/env python3
"""Example: Calculator MCP Server.

This example demonstrates how to create an in-process MCP server with
calculator tools using the Claude Code Python SDK.

Unlike external MCP servers that require separate processes, this server
runs directly within your Python application, providing better performance
and simpler deployment.
"""

import asyncio
from typing import Any

from claude_code_sdk import (
    ClaudeCodeOptions,
    create_sdk_mcp_server,
    query,
    tool,
)

# Define calculator tools using the @tool decorator

@tool("add", "Add two numbers", {"a": float, "b": float})
async def add_numbers(args: dict[str, Any]) -> dict[str, Any]:
    """Add two numbers together."""
    result = args["a"] + args["b"]
    return {
        "content": [
            {
                "type": "text",
                "text": f"{args['a']} + {args['b']} = {result}"
            }
        ]
    }


@tool("subtract", "Subtract one number from another", {"a": float, "b": float})
async def subtract_numbers(args: dict[str, Any]) -> dict[str, Any]:
    """Subtract b from a."""
    result = args["a"] - args["b"]
    return {
        "content": [
            {
                "type": "text",
                "text": f"{args['a']} - {args['b']} = {result}"
            }
        ]
    }


@tool("multiply", "Multiply two numbers", {"a": float, "b": float})
async def multiply_numbers(args: dict[str, Any]) -> dict[str, Any]:
    """Multiply two numbers."""
    result = args["a"] * args["b"]
    return {
        "content": [
            {
                "type": "text",
                "text": f"{args['a']} × {args['b']} = {result}"
            }
        ]
    }


@tool("divide", "Divide one number by another", {"a": float, "b": float})
async def divide_numbers(args: dict[str, Any]) -> dict[str, Any]:
    """Divide a by b."""
    if args["b"] == 0:
        return {
            "content": [
                {
                    "type": "text",
                    "text": "Error: Division by zero is not allowed"
                }
            ],
            "is_error": True
        }

    result = args["a"] / args["b"]
    return {
        "content": [
            {
                "type": "text",
                "text": f"{args['a']} ÷ {args['b']} = {result}"
            }
        ]
    }


@tool("sqrt", "Calculate square root", {"n": float})
async def square_root(args: dict[str, Any]) -> dict[str, Any]:
    """Calculate the square root of a number."""
    n = args["n"]
    if n < 0:
        return {
            "content": [
                {
                    "type": "text",
                    "text": f"Error: Cannot calculate square root of negative number {n}"
                }
            ],
            "is_error": True
        }

    import math
    result = math.sqrt(n)
    return {
        "content": [
            {
                "type": "text",
                "text": f"√{n} = {result}"
            }
        ]
    }


@tool("power", "Raise a number to a power", {"base": float, "exponent": float})
async def power(args: dict[str, Any]) -> dict[str, Any]:
    """Raise base to the exponent power."""
    result = args["base"] ** args["exponent"]
    return {
        "content": [
            {
                "type": "text",
                "text": f"{args['base']}^{args['exponent']} = {result}"
            }
        ]
    }


async def main():
    """Run example calculations using the SDK MCP server."""

    # Create the calculator server with all tools
    calculator = create_sdk_mcp_server(
        name="calculator",
        version="2.0.0",
        tools=[
            add_numbers,
            subtract_numbers,
            multiply_numbers,
            divide_numbers,
            square_root,
            power
        ]
    )

    # Configure Claude to use the calculator server
    options = ClaudeCodeOptions(
        mcp_servers={"calc": calculator},
        # Allow Claude to use calculator tools without permission prompts
        permission_mode="bypassPermissions"
    )

    # Example prompts to demonstrate calculator usage
    prompts = [
        "Calculate 15 + 27",
        "What is 100 divided by 7?",
        "Calculate the square root of 144",
        "What is 2 raised to the power of 8?",
        "Calculate (12 + 8) * 3 - 10"  # Complex calculation
    ]

    for prompt in prompts:
        print(f"\n{'='*50}")
        print(f"Prompt: {prompt}")
        print(f"{'='*50}")

        async for message in query(prompt=prompt, options=options):
            # Print the message content
            if hasattr(message, 'content'):
                for content_block in message.content:
                    if hasattr(content_block, 'text'):
                        print(f"Claude: {content_block.text}")
                    elif hasattr(content_block, 'name'):
                        print(f"Using tool: {content_block.name}")


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