Fix workspace configuration error with structured_output_lowlevel.py (#1471)

Co-authored-by: lorenss-m <saeclmusic@gmail.com>

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

@@ -0,0 +1 @@
+"""Example of structured output with low-level MCP server."""

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

@@ -0,0 +1,98 @@
+#!/usr/bin/env python3
+"""
+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
+schemas.
+"""
+
+import asyncio
+from datetime import datetime
+from typing import Any
+
+import mcp.server.stdio
+import mcp.types as types
+from mcp.server.lowlevel import NotificationOptions, Server
+from mcp.server.models import InitializationOptions
+
+# Create low-level server instance
+server = Server("structured-output-lowlevel-example")
+
+
+@server.list_tools()
+async def list_tools() -> list[types.Tool]:
+    """List available tools with their schemas."""
+    return [
+        types.Tool(
+            name="get_weather",
+            description="Get weather information (simulated)",
+            inputSchema={
+                "type": "object",
+                "properties": {"city": {"type": "string", "description": "City name"}},
+                "required": ["city"],
+            },
+            outputSchema={
+                "type": "object",
+                "properties": {
+                    "temperature": {"type": "number"},
+                    "conditions": {"type": "string"},
+                    "humidity": {"type": "integer", "minimum": 0, "maximum": 100},
+                    "wind_speed": {"type": "number"},
+                    "timestamp": {"type": "string", "format": "date-time"},
+                },
+                "required": ["temperature", "conditions", "humidity", "wind_speed", "timestamp"],
+            },
+        ),
+    ]
+
+
+@server.call_tool()
+async def call_tool(name: str, arguments: dict[str, Any]) -> Any:
+    """
+    Handle tool call with structured output.
+    """
+
+    if name == "get_weather":
+        # city = arguments["city"]  # Would be used with real weather API
+
+        # Simulate weather data (in production, call a real weather API)
+        import random
+
+        weather_conditions = ["sunny", "cloudy", "rainy", "partly cloudy", "foggy"]
+
+        weather_data = {
+            "temperature": round(random.uniform(0, 35), 1),
+            "conditions": random.choice(weather_conditions),
+            "humidity": random.randint(30, 90),
+            "wind_speed": round(random.uniform(0, 30), 1),
+            "timestamp": datetime.now().isoformat(),
+        }
+
+        # Return structured data only
+        # The low-level server will serialize this to JSON content automatically
+        return weather_data
+
+    else:
+        raise ValueError(f"Unknown tool: {name}")
+
+
+async def run():
+    """Run the low-level server using stdio transport."""
+    async with mcp.server.stdio.stdio_server() as (read_stream, write_stream):
+        await server.run(
+            read_stream,
+            write_stream,
+            InitializationOptions(
+                server_name="structured-output-lowlevel-example",
+                server_version="0.1.0",
+                capabilities=server.get_capabilities(
+                    notification_options=NotificationOptions(),
+                    experimental_capabilities={},
+                ),
+            ),
+        )
+
+
+if __name__ == "__main__":
+    asyncio.run(run())

examples/servers/structured-output-lowlevel/pyproject.toml

@@ -0,0 +1,6 @@
+[project]
+name = "mcp-structured-output-lowlevel"
+version = "0.1.0"
+description = "Example of structured output with low-level MCP server"
+requires-python = ">=3.10"
+dependencies = ["mcp"]

uv.lock

@@ -1,5 +1,5 @@
 version = 1
-revision = 2
+revision = 3
 requires-python = ">=3.10"
 
 [manifest]
@@ -13,6 +13,7 @@ members = [
     "mcp-simple-streamablehttp-stateless",
     "mcp-simple-tool",
     "mcp-snippets",
+    "mcp-structured-output-lowlevel",
 ]
 
 [[package]]
@@ -948,6 +949,17 @@ dependencies = [
 [package.metadata]
 requires-dist = [{ name = "mcp", editable = "." }]
 
+[[package]]
+name = "mcp-structured-output-lowlevel"
+version = "0.1.0"
+source = { virtual = "examples/servers/structured-output-lowlevel" }
+dependencies = [
+    { name = "mcp" },
+]
+
+[package.metadata]
+requires-dist = [{ name = "mcp", editable = "." }]
+
 [[package]]
 name = "mdurl"
 version = "0.1.2"