Human in the loop (HITL) let’s you get input from a user before or after executing a tool call.

The example below shows how to use a pre-hook to get user confirmation before executing a tool call. But we can very easily do the same in a post-hook as well.

​
Example: Human in the loop using pre-hooks

This example shows how to:

  • Add pre-hooks to tools for user confirmation
  • Handle user input during tool execution
  • Gracefully cancel operations based on user choice
hitl.py
"""🤝 Human-in-the-Loop: Adding User Confirmation to Tool Calls

This example shows how to implement human-in-the-loop functionality in your Agno tools.
It shows how to:
- Add pre-hooks to tools for user confirmation
- Handle user input during tool execution
- Gracefully cancel operations based on user choice

Some practical applications:
- Confirming sensitive operations before execution
- Reviewing API calls before they're made
- Validating data transformations
- Approving automated actions in critical systems

Run `pip install openai httpx rich agno` to install dependencies.
"""

import json
from typing import Iterator

import httpx
from agno.agent import Agent
from agno.exceptions import StopAgentRun
from agno.models.openai import OpenAIChat
from agno.tools import FunctionCall, tool
from rich.console import Console
from rich.pretty import pprint
from rich.prompt import Prompt

# This is the console instance used by the print_response method
# We can use this to stop and restart the live display and ask for user confirmation
console = Console()


def pre_hook(fc: FunctionCall):
    # Get the live display instance from the console
    live = console._live

    # Stop the live display temporarily so we can ask for user confirmation
    live.stop()  # type: ignore

    # Ask for confirmation
    console.print(f"\nAbout to run [bold blue]{fc.function.name}[/]")
    message = (
        Prompt.ask("Do you want to continue?", choices=["y", "n"], default="y")
        .strip()
        .lower()
    )

    # Restart the live display
    live.start()  # type: ignore

    # If the user does not want to continue, raise a StopExecution exception
    if message != "y":
        raise StopAgentRun(
            "Tool call cancelled by user",
            agent_message="Stopping execution as permission was not granted.",
        )


@tool(pre_hook=pre_hook)
def get_top_hackernews_stories(num_stories: int) -> Iterator[str]:
    """Fetch top stories from Hacker News after user confirmation.

    Args:
        num_stories (int): Number of stories to retrieve

    Returns:
        str: JSON string containing story details
    """
    # Fetch top story IDs
    response = httpx.get("https://hacker-news.firebaseio.com/v0/topstories.json")
    story_ids = response.json()

    # Yield story details
    for story_id in story_ids[:num_stories]:
        story_response = httpx.get(
            f"https://hacker-news.firebaseio.com/v0/item/{story_id}.json"
        )
        story = story_response.json()
        if "text" in story:
            story.pop("text", None)
        yield json.dumps(story)


# Initialize the agent with a tech-savvy personality and clear instructions
agent = Agent(
    model=OpenAIChat(id="gpt-4o-mini"),
    tools=[get_top_hackernews_stories],
    markdown=True,
)

agent.print_response(
    "Fetch the top 2 hackernews stories?", stream=True, console=console
)