{
  "name": "Read",
  "description": "Reads a file from the filesystem.
    Use this to read files before editing.
    Returns content with line numbers.",
  "input_schema": {
    "type": "object",
    "properties": {
      "file_path": {
        "type": "string",
        "description": "Absolute path to file"
      },
      "offset": {
        "type": "number",
        "description": "Start line number"
      },
      "limit": {
        "type": "number",
        "description": "Number of lines to read"
      }
    },
    "required": ["file_path"]
  }
}

{
  "name": "get_weather",
  "description": "Get current weather for a city.
    Use when user asks about weather
    or needs temperature data.",
  "input_schema": {
    "type": "object",
    "properties": {
      "city": {
        "type": "string",
        "description": "City name, e.g. Moscow"
      },
      "units": {
        "type": "string",
        "enum": ["celsius", "fahrenheit"],
        "description": "Temperature units"
      }
    },
    "required": ["city"]
  }
}

Запрос

import anthropic

client = anthropic.Anthropic()

response = client.messages.create(
    model="claude-sonnet-4-20250514",
    max_tokens=1024,
    tools=[{
        "name": "get_weather",
        "description": "Get current weather",
        "input_schema": {
            "type": "object",
            "properties": {
                "city": {"type": "string"}
            },
            "required": ["city"]
        }
    }],
    messages=[{
        "role": "user",
        "content": "Какая погода в Москве?"
    }]
)

Ответ модели

{
  "role": "assistant",
  "content": [
    {
      "type": "tool_use",
      "id": "toolu_01A...",
      "name": "get_weather",
      "input": {"city": "Moscow"}
    }
  ],
  "stop_reason": "tool_use"
}

Отправляем результат

# Получили tool_use от модели
tool_block = response.content[0]

# Выполняем действие
weather = call_weather_api(
    tool_block.input["city"]
)

# Отправляем результат обратно
final = client.messages.create(
    model="claude-sonnet-4-20250514",
    tools=tools,
    messages=[
        {"role": "user",
         "content": "Погода в Москве?"},
        {"role": "assistant",
         "content": response.content},
        {"role": "user",
         "content": [{
           "type": "tool_result",
           "tool_use_id": tool_block.id,
           "content": json.dumps(weather)
         }]}
    ]
)

from mcp.server.fastmcp import FastMCP

mcp = FastMCP("demo-server")

@mcp.tool()
def add(a: int, b: int) -> int:
    """Add two numbers together."""
    return a + b

@mcp.tool()
def get_time() -> str:
    """Get current server time."""
    from datetime import datetime
    return datetime.now().isoformat()

@mcp.resource("config://app")
def get_config() -> str:
    """Application configuration."""
    return "debug=true, version=1.0"

if __name__ == "__main__":
    mcp.run()

Claude Code (.mcp.json)

{
  "mcpServers": {
    "demo": {
      "command": "python",
      "args": ["server.py"]
    },
    "github": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-github"
      ],
      "env": {
        "GITHUB_TOKEN": "ghp_..."
      }
    }
  }
}

VS Code / Cursor (.vscode/mcp.json)

{
  "servers": {
    "demo": {
      "type": "stdio",
      "command": "python",
      "args": ["server.py"]
    }
  }
}