SEP-1686: Tasks (#1645)

examples/servers/simple-task/mcp_simple_task/server.py

@@ -0,0 +1,84 @@
+"""Simple task server demonstrating MCP tasks over streamable HTTP."""
+
+from collections.abc import AsyncIterator
+from contextlib import asynccontextmanager
+from typing import Any
+
+import anyio
+import click
+import mcp.types as types
+import uvicorn
+from mcp.server.experimental.task_context import ServerTaskContext
+from mcp.server.lowlevel import Server
+from mcp.server.streamable_http_manager import StreamableHTTPSessionManager
+from starlette.applications import Starlette
+from starlette.routing import Mount
+
+server = Server("simple-task-server")
+
+# One-line setup: auto-registers get_task, get_task_result, list_tasks, cancel_task
+server.experimental.enable_tasks()
+
+
+@server.list_tools()
+async def list_tools() -> list[types.Tool]:
+    return [
+        types.Tool(
+            name="long_running_task",
+            description="A task that takes a few seconds to complete with status updates",
+            inputSchema={"type": "object", "properties": {}},
+            execution=types.ToolExecution(taskSupport=types.TASK_REQUIRED),
+        )
+    ]
+
+
+async def handle_long_running_task(arguments: dict[str, Any]) -> types.CreateTaskResult:
+    """Handle the long_running_task tool - demonstrates status updates."""
+    ctx = server.request_context
+    ctx.experimental.validate_task_mode(types.TASK_REQUIRED)
+
+    async def work(task: ServerTaskContext) -> types.CallToolResult:
+        await task.update_status("Starting work...")
+        await anyio.sleep(1)
+
+        await task.update_status("Processing step 1...")
+        await anyio.sleep(1)
+
+        await task.update_status("Processing step 2...")
+        await anyio.sleep(1)
+
+        return types.CallToolResult(content=[types.TextContent(type="text", text="Task completed!")])
+
+    return await ctx.experimental.run_task(work)
+
+
+@server.call_tool()
+async def handle_call_tool(name: str, arguments: dict[str, Any]) -> types.CallToolResult | types.CreateTaskResult:
+    """Dispatch tool calls to their handlers."""
+    if name == "long_running_task":
+        return await handle_long_running_task(arguments)
+    else:
+        return types.CallToolResult(
+            content=[types.TextContent(type="text", text=f"Unknown tool: {name}")],
+            isError=True,
+        )
+
+
+@click.command()
+@click.option("--port", default=8000, help="Port to listen on")
+def main(port: int) -> int:
+    session_manager = StreamableHTTPSessionManager(app=server)
+
+    @asynccontextmanager
+    async def app_lifespan(app: Starlette) -> AsyncIterator[None]:
+        async with session_manager.run():
+            yield
+
+    starlette_app = Starlette(
+        routes=[Mount("/mcp", app=session_manager.handle_request)],
+        lifespan=app_lifespan,
+    )
+
+    print(f"Starting server on http://localhost:{port}/mcp")
+    uvicorn.run(starlette_app, host="127.0.0.1", port=port)
+    return 0