pydantic-mcp-client-server-example.py

gistfile1.py

# You'll need to save the 2 files separately in the same dir to run.

# mcp-server.py =================================================================================
from pathlib import Path

from mcp.server.fastmcp import FastMCP

server = FastMCP('Pydantic AI Server')

@server.tool()
def sum(a: int, b: int) -> int:
    """Add two numbers"""
    return a + b

@server.resource("dir://desktop")
def desktop() -> list[str]:
    """List the files in the user's desktop"""
    desktop = Path.home() / "Desktop"
    return [str(f) for f in desktop.iterdir()]

@server.prompt("echo")
def echo_prompt(text: str) -> str:
    return text


if __name__ == '__main__':
    server.run()

# mcp-client.py =================================================================================
import asyncio
import os
import json

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


async def client():
    server_params = StdioServerParameters(
        command='python', args=['scratch-mcp-server.py'],
    )
    async with stdio_client(server_params) as (read, write):
        async with ClientSession(read, write) as session:
            await session.initialize()
            # list tools
            tools = await session.list_tools()
            print(f'Available tools are: {tools.model_dump_json(indent=2)}')

            # call tool
            result = await session.call_tool('sum', {'a': 1, 'b': 2})
            print(f'Sum is: {result.content[0].text}')

            resource_result = await session.read_resource('dir://desktop')
            print(f'Desktop Files are: {resource_result.contents[0].text}')

            # now prompt
            prompt_result = await session.get_prompt('echo', {'text': 'This text will be echoed back!'})
            print(f'Echoed text is: {prompt_result.messages[0].content.text}')

            
if __name__ == '__main__':
    asyncio.run(client())

"""
Available tools are: {
  "meta": null,
  "nextCursor": null,
  "tools": [
    {
      "name": "sum",
      "title": null,
      "description": "Add two numbers",
      "inputSchema": {
        "properties": {
          "a": {
            "title": "A",
            "type": "integer"
          },
          "b": {
            "title": "B",
            "type": "integer"
          }
        },
        "required": [
          "a",
          "b"
        ],
        "title": "sumArguments",
        "type": "object"
      },
      "outputSchema": {
        "properties": {
          "result": {
            "title": "Result",
            "type": "integer"
          }
        },
        "required": [
          "result"
        ],
        "title": "sumOutput",
        "type": "object"
      },
      "annotations": null,
      "meta": null
    }
  ]
}
Sum is: 3
Desktop Files are: [
  "/home/my-user/Desktop/New Folder",
]
Echoed text is: This text will be echoed back!
"""