Progress Monitoring - Fastmcp

import { VersionBadge } from '/snippets/version-badge.mdx'

MCP servers can report progress during long-running operations. The client can receive these updates through a progress handler.

Progress Handler

Set a progress handler when creating the client:

python

from fastmcp import Client

async def my_progress_handler(
    progress: float, 
    total: float | None, 
    message: str | None
) -> None:
    if total is not None:
        percentage = (progress / total) * 100
        print(f"Progress: {percentage:.1f}% - {message or ''}")
    else:
        print(f"Progress: {progress} - {message or ''}")

client = Client(
    "my_mcp_server.py",
    progress_handler=my_progress_handler
)

Handler Parameters

The progress handler receives three parameters:

<Card icon="code" title="Progress Handler Parameters"> <ResponseField name="progress" type="float"> Current progress value </ResponseField> <ResponseField name="total" type="float | None"> Expected total value (may be None) </ResponseField> <ResponseField name="message" type="str | None"> Optional status message (may be None) </ResponseField> </Card>

Per-Call Progress Handler

Override the progress handler for specific tool calls:

python

async with client:
    # Override with specific progress handler for this call
    result = await client.call_tool(
        "long_running_task", 
        {"param": "value"}, 
        progress_handler=my_progress_handler
    )