adk_custom_tool_agent

ADK Function Tool - Order Status

An ADK agent that demonstrates creating custom function tools. This agent uses a FunctionTool to check order status.

Overview

This agent shows how to create custom tools using the FunctionTool wrapper. The agent can check the status of orders using a custom function.

What is a Function Tool? A Function Tool allows you to wrap any Python function and make it available to your ADK agent. The agent can automatically call these functions based on user queries, enabling it to perform custom operations beyond built-in capabilities.

Project Structure

adk_custom_tool_agent/
├── agent.py         # Main agent code with custom FunctionTool
├── __init__.py      # Package initialization
└── .env.example     # Example environment variables template

Prerequisites

• Python 3.11 or later
• Google ADK installed (see parent directory README for installation instructions)
• Google API key from Google AI Studio

Setup

1. Create a .env file with your API key and configuration:

Copy the example environment file and update it with your API key:

cp .env.example .env

Then edit .env and replace "your-api-key" (or "YOUR_API_KEY") with your actual Google API key.

Environment Variables:

• GOOGLE_GENAI_USE_VERTEXAI=False: Use AI Studio (Gemini API) instead of Vertex AI
• GOOGLE_API_KEY: Your Google API key from Google AI Studio

Usage

Run with Command Line Interface

From the 1_adk_tools directory:

adk run adk_custom_tool_agent

Run with Web Interface

From the 1_adk_tools directory:

adk web

Then open the URL shown in the terminal (typically http://localhost:8000) in your browser and select the agent.

Agent Details

• Google ADK Version: 1.18.0
• Model: gemini-2.5-flash
• Tool: Custom FunctionTool wrapping get_order_status function
• Capabilities: Check order status by order ID

Custom Tool Implementation

The agent includes a custom function:

def get_order_status(order_id: str):
    """Retrieves the status of an order by order ID."""
    return {"order_id": order_id, "status": "Shipped", "delivery_date": "Nov 4, 2025"}

This function is wrapped with FunctionTool to make it available to the agent:

tools=[FunctionTool(get_order_status)]

Demo

Extending the Tool

You can extend this example by:

• Connecting to a real order database
• Adding more order-related functions
• Implementing authentication
• Adding error handling

References

• ADK Documentation
• Function Tools
• Python Quickstart