MCPサーバーを自作する方法【Python/Node.js実装例】

pipinstallfastmcp

# server.py
fromfastmcpimport FastMCP

mcp = FastMCP("my-tools")

@mcp.tool()
defread_file(path: str) -> str:
   """指定したパスのファイルを読み込む"""
    with open(path, 'r', encoding='utf-8') as f:
        return f.read()

@mcp.tool()
deflist_directory(path: str) -> list[str]:
   """ディレクトリ内のファイル一覧を返す"""
    importos
    return os.listdir(path)

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

fromfastmcpimport FastMCP
frompydanticimport BaseModel

mcp = FastMCP("image-tools")

classResizeParams(BaseModel):
    input_path: str
    output_path: str
    width: int
    height: int

@mcp.tool()
defresize_image(params: ResizeParams) -> str:
   """画像をリサイズする"""
    fromPILimport Image
    img = Image.open(params.input_path)
    img_resized = img.resize((params.width, params.height))
    img_resized.save(params.output_path)
    return f"Resized to{params.width}x{params.height}:{params.output_path}"

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

npminstall@modelcontextprotocol/sdk

// server.ts
import{Server}from"@modelcontextprotocol/sdk/server/index.js";
import{StdioServerTransport}from"@modelcontextprotocol/sdk/server/stdio.js";
import{CallToolRequestSchema,ListToolsRequestSchema}from"@modelcontextprotocol/sdk/types.js";

constserver=newServer(
 {name:"my-ts-tools",version:"1.0.0"},
 {capabilities:{tools:{}}}
);

server.setRequestHandler(ListToolsRequestSchema,async()=>({
 tools:[{
   name:"get_current_time",
   description:"現在時刻を返す",
   inputSchema:{type:"object",properties:{}}
 }]
}));

server.setRequestHandler(CallToolRequestSchema,async(request)=>{
 if(request.params.name==="get_current_time"){
   return{content:[{type:"text",text:newDate().toISOString()}]};
 }
 thrownewError("Unknown tool");
});

consttransport=newStdioServerTransport();
awaitserver.connect(transport);

{
 "mcpServers":{
   "my-tools":{
     "command":"python",
     "args":["/absolute/path/to/server.py"],
     "env":{}
   }
 }
}

{
 "mcpServers":{
   "my-ts-tools":{
     "command":"node",
     "args":["/absolute/path/to/dist/server.js"],
     "env":{}
   }
 }
}

{
 "mcpServers":{
   "my-tools":{
     "command":"python",
     "args":["C:/absolute/path/to/server.py"]
   }
 }
}

# image_editor_mcp.py
importhttpx
fromfastmcpimport FastMCP

mcp = FastMCP("image-editor")
BASE_URL = "http://localhost:8766"

@mcp.tool()
defapply_filter(image_path: str, filter_name: str) -> str:
   """画像にフィルターを適用する。filter_name: blur / sharpen / grayscale"""
    resp = httpx.post(f"{BASE_URL}/apply", json={
        "path": image_path,
        "filter": filter_name
    })
    return resp.json()["result_path"]

@mcp.tool()
defcrop_image(image_path: str, x: int, y: int, width: int, height: int) -> str:
   """画像をクロップする"""
    resp = httpx.post(f"{BASE_URL}/crop", json={
        "path": image_path,
        "x": x, "y": y, "width": width, "height": height
    })
    return resp.json()["result_path"]

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