156 lines
5.6 KiB
Python
156 lines
5.6 KiB
Python
"""Simple interactive task server demonstrating elicitation and sampling.
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This example shows the simplified task API where:
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- server.experimental.enable_tasks() sets up all infrastructure
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- ctx.experimental.run_task() handles task lifecycle automatically
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- ServerTaskContext.elicit() and ServerTaskContext.create_message() queue requests properly
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"""
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from collections.abc import AsyncIterator
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from contextlib import asynccontextmanager
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from typing import Any
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import click
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import uvicorn
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from mcp import types
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from mcp.server import Server, ServerRequestContext
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from mcp.server.experimental.task_context import ServerTaskContext
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from mcp.server.streamable_http_manager import StreamableHTTPSessionManager
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from starlette.applications import Starlette
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from starlette.routing import Mount
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async def handle_list_tools(
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ctx: ServerRequestContext, params: types.PaginatedRequestParams | None
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) -> types.ListToolsResult:
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return types.ListToolsResult(
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tools=[
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types.Tool(
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name="confirm_delete",
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description="Asks for confirmation before deleting (demonstrates elicitation)",
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input_schema={
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"type": "object",
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"properties": {"filename": {"type": "string"}},
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},
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execution=types.ToolExecution(task_support=types.TASK_REQUIRED),
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),
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types.Tool(
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name="write_haiku",
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description="Asks LLM to write a haiku (demonstrates sampling)",
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input_schema={"type": "object", "properties": {"topic": {"type": "string"}}},
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execution=types.ToolExecution(task_support=types.TASK_REQUIRED),
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),
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]
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)
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async def handle_confirm_delete(ctx: ServerRequestContext, arguments: dict[str, Any]) -> types.CreateTaskResult:
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"""Handle the confirm_delete tool - demonstrates elicitation."""
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ctx.experimental.validate_task_mode(types.TASK_REQUIRED)
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filename = arguments.get("filename", "unknown.txt")
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print(f"\n[Server] confirm_delete called for '{filename}'")
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async def work(task: ServerTaskContext) -> types.CallToolResult:
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print(f"[Server] Task {task.task_id} starting elicitation...")
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result = await task.elicit(
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message=f"Are you sure you want to delete '{filename}'?",
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requested_schema={
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"type": "object",
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"properties": {"confirm": {"type": "boolean"}},
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"required": ["confirm"],
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},
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)
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print(f"[Server] Received elicitation response: action={result.action}, content={result.content}")
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if result.action == "accept" and result.content:
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confirmed = result.content.get("confirm", False)
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text = f"Deleted '{filename}'" if confirmed else "Deletion cancelled"
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else:
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text = "Deletion cancelled"
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print(f"[Server] Completing task with result: {text}")
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return types.CallToolResult(content=[types.TextContent(type="text", text=text)])
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return await ctx.experimental.run_task(work)
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async def handle_write_haiku(ctx: ServerRequestContext, arguments: dict[str, Any]) -> types.CreateTaskResult:
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"""Handle the write_haiku tool - demonstrates sampling."""
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ctx.experimental.validate_task_mode(types.TASK_REQUIRED)
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topic = arguments.get("topic", "nature")
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print(f"\n[Server] write_haiku called for topic '{topic}'")
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async def work(task: ServerTaskContext) -> types.CallToolResult:
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print(f"[Server] Task {task.task_id} starting sampling...")
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result = await task.create_message(
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messages=[
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types.SamplingMessage(
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role="user",
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content=types.TextContent(type="text", text=f"Write a haiku about {topic}"),
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)
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],
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max_tokens=50,
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)
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haiku = "No response"
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if isinstance(result.content, types.TextContent):
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haiku = result.content.text
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print(f"[Server] Received sampling response: {haiku[:50]}...")
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return types.CallToolResult(content=[types.TextContent(type="text", text=f"Haiku:\n{haiku}")])
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return await ctx.experimental.run_task(work)
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async def handle_call_tool(
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ctx: ServerRequestContext, params: types.CallToolRequestParams
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) -> types.CallToolResult | types.CreateTaskResult:
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"""Dispatch tool calls to their handlers."""
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arguments = params.arguments or {}
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if params.name == "confirm_delete":
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return await handle_confirm_delete(ctx, arguments)
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elif params.name == "write_haiku":
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return await handle_write_haiku(ctx, arguments)
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return types.CallToolResult(
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content=[types.TextContent(type="text", text=f"Unknown tool: {params.name}")],
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is_error=True,
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)
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server = Server(
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"simple-task-interactive",
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on_list_tools=handle_list_tools,
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on_call_tool=handle_call_tool,
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)
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# Enable task support - this auto-registers all handlers
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server.experimental.enable_tasks()
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def create_app(session_manager: StreamableHTTPSessionManager) -> Starlette:
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@asynccontextmanager
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async def app_lifespan(app: Starlette) -> AsyncIterator[None]:
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async with session_manager.run():
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yield
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return Starlette(
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routes=[Mount("/mcp", app=session_manager.handle_request)],
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lifespan=app_lifespan,
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)
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@click.command()
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@click.option("--port", default=8000, help="Port to listen on")
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def main(port: int) -> int:
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session_manager = StreamableHTTPSessionManager(app=server)
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starlette_app = create_app(session_manager)
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print(f"Starting server on http://localhost:{port}/mcp")
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uvicorn.run(starlette_app, host="127.0.0.1", port=port)
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return 0
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