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74e01d5e08A FastMCP client now transparently completes tasked tools/call: the tasks ClientExtension advertises the capability and claims the CreateTaskResult, and the resolver drives the tasks/get poll loop to completion, answering in-task input through the client's elicitation handler and returning the tool's real result. call_tool is transparent, call_tool_mcp exposes the raw result, and call_tool_task yields a Task handle. The client half moves to fastmcp-tasks; the [tasks] client extension auto-wires into Client (ProxyClient opts out). Co-Authored-By: Claude <noreply@anthropic.com>
124 lines
3.8 KiB
Python
124 lines
3.8 KiB
Python
"""
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FastMCP Tasks Example Client (SEP-2663)
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Demonstrates the two client task surfaces:
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- Transparent: `client.call_tool(...)` drives the background task to completion
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under the hood and returns the tool's real result. The caller writes ordinary
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tool-call code and never sees that the server ran the call as a task.
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- Explicit handle: `call_tool_task(...)` returns a `ToolTask` immediately, so the
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client can do other work and poll the task itself before collecting the result.
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Usage:
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# Make sure environment is configured (source .envrc or use direnv)
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source .envrc
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# Transparent background task (default)
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python client.py --duration 10
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# Return-quickly handle, driven by the client
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python client.py handle --duration 5
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"""
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import asyncio
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import sys
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from pathlib import Path
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from typing import Annotated
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import cyclopts
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from mcp_types import TextContent
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from rich.console import Console
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from fastmcp.client import Client
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from fastmcp_tasks import call_tool_task
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console = Console()
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app = cyclopts.App(name="tasks-client", help="FastMCP Tasks Example Client")
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def load_server():
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"""Load the example server."""
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examples_dir = Path(__file__).parent.parent.parent
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if str(examples_dir) not in sys.path:
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sys.path.insert(0, str(examples_dir))
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import examples.tasks.server as server_module
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return server_module.mcp
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@app.default
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async def transparent(
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duration: Annotated[
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int,
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cyclopts.Parameter(help="Duration of computation in seconds (1-60)"),
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] = 10,
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):
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"""Call the tool transparently: the client drives the task to completion."""
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if duration < 1 or duration > 60:
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console.print("[red]Error: Duration must be between 1 and 60 seconds[/red]")
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sys.exit(1)
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server = load_server()
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console.print(f"\n[bold]Calling slow_computation(duration={duration})[/bold]")
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console.print("Mode: [cyan]Transparent (server may run it as a task)[/cyan]\n")
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# mode="auto" negotiates the modern protocol, so the server may run the call
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# as a background task; the client resolves it transparently.
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async with Client(server, mode="auto") as client:
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result = await client.call_tool(
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"slow_computation",
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arguments={"duration": duration},
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)
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console.print("\n[bold]Result:[/bold]")
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assert isinstance(result.content[0], TextContent)
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console.print(f" {result.content[0].text}")
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@app.command
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async def handle(
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duration: Annotated[
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int,
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cyclopts.Parameter(help="Duration of computation in seconds (1-60)"),
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] = 5,
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):
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"""Use the explicit handle: return immediately, then drive the task."""
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if duration < 1 or duration > 60:
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console.print("[red]Error: Duration must be between 1 and 60 seconds[/red]")
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sys.exit(1)
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server = load_server()
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console.print(f"\n[bold]Calling slow_computation(duration={duration})[/bold]")
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console.print("Mode: [cyan]Explicit ToolTask handle[/cyan]\n")
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async with Client(server, mode="auto") as client:
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task = await call_tool_task(
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client,
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"slow_computation",
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arguments={"duration": duration},
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)
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console.print(f"Task started: [cyan]{task.task_id}[/cyan]\n")
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# Do other work while the task runs in the background.
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for i in range(3):
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await asyncio.sleep(0.5)
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status = await task.status()
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console.print(
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f"[dim]Client doing other work... ({i + 1}/3) "
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f"— task is {status.status}[/dim]"
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)
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console.print("\n[dim]Waiting for the final result...[/dim]")
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result = await task.result()
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console.print("\n[bold]Result:[/bold]")
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assert isinstance(result.content[0], TextContent)
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console.print(f" {result.content[0].text}")
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if __name__ == "__main__":
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app()
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