chore: add D212 lint rule to enforce Google-style docstrings (#1892)

examples/servers/structured-output-lowlevel/mcp_structured_output_lowlevel/__main__.py

@@ -1,6 +1,5 @@
 #!/usr/bin/env python3
-"""
-Example low-level MCP server demonstrating structured output support.
+"""Example low-level MCP server demonstrating structured output support.
 
 This example shows how to use the low-level server API to return
 structured data from tools, with automatic validation against output
@@ -49,9 +48,7 @@ async def list_tools() -> list[types.Tool]:
 
 @server.call_tool()
 async def call_tool(name: str, arguments: dict[str, Any]) -> Any:
-    """
-    Handle tool call with structured output.
-    """
+    """Handle tool call with structured output."""
 
     if name == "get_weather":
         # city = arguments["city"]  # Would be used with real weather API