Any python function can be used as a tool by an Agent. We highly recommend creating functions specific to your workflow and adding them to your Agents.

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Custom Python Function Example

For example, here’s how to use a get_top_hackernews_stories function as a tool:

hn_agent.py
import json
import httpx

from agno.agent import Agent

def get_top_hackernews_stories(num_stories: int = 10) -> str:
    """
    Use this function to get top stories from Hacker News.

    Args:
        num_stories (int): Number of stories to return. Defaults to 10.

    Returns:
        str: JSON string of top stories.
    """

    # Fetch top story IDs
    response = httpx.get('https://hacker-news.firebaseio.com/v0/topstories.json')
    story_ids = response.json()

    # Fetch story details
    stories = []
    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)
        stories.append(story)
    return json.dumps(stories)

agent = Agent(tools=[get_top_hackernews_stories], show_tool_calls=True, markdown=True)
agent.print_response("Summarize the top 5 stories on hackernews?", stream=True)

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Using the @tool Decorator

For more flexibility, you can use the @tool decorator to quickly create agent-ready functions without creating a full Toolkit class. This approach is more concise and ideal for single-purpose tools.

The @tool decorator supports several parameters to customize tool behavior:

advanced_tool.py
import httpx
from agno.agent import Agent
from agno.tools import tool

def log_before_call(fc):
    """Pre-hook function that runs before the tool execution"""
    print(f"About to call function with arguments: {fc.arguments}")

def log_after_call(fc):
    """Post-hook function that runs after the tool execution"""
    print(f"Function call completed with result: {fc.result}")

@tool(
    name="fetch_hackernews_stories",                # Custom name for the tool (otherwise the function name is used)
    description="Get top stories from Hacker News",  # Custom description (otherwise the function docstring is used)
    show_result=True,                               # Show result after function call
    stop_after_tool_call=True,                      # Return the result immediately after the tool call and stop the agent
    pre_hook=log_before_call,                       # Hook to run before execution
    post_hook=log_after_call,                       # Hook to run after execution
    cache_results=True,                             # Enable caching of results
    cache_dir="/tmp/agno_cache",                    # Custom cache directory
    cache_ttl=3600                                  # Cache TTL in seconds (1 hour)
)
def get_top_hackernews_stories(num_stories: int = 5) -> str:
    """
    Fetch the top stories from Hacker News.
    
    Args:
        num_stories: Number of stories to fetch (default: 5)
    
    Returns:
        str: The top stories in text format
    """
    # Fetch top story IDs
    response = httpx.get("https://hacker-news.firebaseio.com/v0/topstories.json")
    story_ids = response.json()

    # Get story details
    stories = []
    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()
        stories.append(f"{story.get('title')} - {story.get('url', 'No URL')}")

    return "\n".join(stories)

agent = Agent(tools=[get_top_hackernews_stories])
agent.print_response("Show me the top news from Hacker News")

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@tool Parameters Reference

ParameterTypeDescription
namestrOverride for the function name
descriptionstrOverride for the function description
show_resultboolIf True, shows the result after function call
stop_after_tool_callboolIf True, the agent will stop after the function call
pre_hookcallableHook that runs before the function is executed
post_hookcallableHook that runs after the function is executed
cache_resultsboolIf True, enable caching of function results
cache_dirstrDirectory to store cache files
cache_ttlintTime-to-live for cached results in seconds (default: 3600)