🧰 Beispielserver: die offiziellen Referenzserver

const server = new McpServer({ name: "secure-filesystem-server", version: "0.2.0" }, …);

server.registerTool(
  "write_file",
  {
    title: "Write File",
    description: "Create a new file or completely overwrite an existing file with new content. …",
    inputSchema: {
      path: z.string(),
      content: z.string()
    },
    outputSchema: { content: z.string() },
    annotations: { readOnlyHint: false, idempotentHint: true, destructiveHint: true, openWorldHint: false }
  },
  async (args) => {
    const validPath = await validatePath(args.path);     // nur erlaubte Verzeichnisse
    await writeFileContent(validPath, args.content);
    const text = `Successfully wrote to ${args.path}`;
    return {
      content: [{ type: "text", text }],
      structuredContent: { content: text }
    };
  }
);

class Fetch(BaseModel):
    """Parameters for fetching a URL."""
    url: Annotated[AnyUrl, Field(description="URL to fetch")]
    max_length: Annotated[int, Field(default=5000,
        description="Maximum number of characters to return.", gt=0, lt=1000000)]
    start_index: Annotated[int, Field(default=0, description="…", ge=0)]
    raw: Annotated[bool, Field(default=False, description="…")]

server = Server("mcp-fetch")

@server.list_tools()
async def list_tools() -> list[Tool]:
    return [Tool(name="fetch", description="…", inputSchema=Fetch.model_json_schema())]

@server.call_tool()
async def call_tool(name, arguments: dict) -> list[TextContent]:
    args = Fetch(**arguments)                       # Validierung durch Pydantic
    …
    return [TextContent(type="text", text=f"{prefix}Contents of {url}:\n{content}")]

Tool(
    name="get_current_time",
    description="Get current time in a specific timezone",
    inputSchema={
        "type": "object",
        "properties": {
            "timezone": {
                "type": "string",
                "description": f"IANA timezone name (…). Use '{local_tz}' as local timezone …",
            }
        },
        "required": ["timezone"],
    },
    annotations=ToolAnnotations(readOnlyHint=True, destructiveHint=False,
                                idempotentHint=True, openWorldHint=False),
)

{
  "mcpServers": {
    "filesystem": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-filesystem",
        "/projekt"
      ]
    },
    "fetch": {
      "command": "uvx",
      "args": [
        "mcp-server-fetch"
      ]
    },
    "time": {
      "command": "uvx",
      "args": [
        "mcp-server-time",
        "--local-timezone=Europe/Berlin"
      ]
    },
    "memory": {
      "command": "npx",
      "args": [
        "-y",
        "@modelcontextprotocol/server-memory"
      ],
      "env": {
        "MEMORY_FILE_PATH": "/daten/memory.json"
      }
    },
    "beispiel-remote": {
      "type": "http",
      "url": "https://mcp.example.org/mcp"
    }
  }
}