In this article, I will show you how to build your first AI agent from scratch using Google’s ADK (Agent Development Kit). This is an open-source framework that makes it easier to create agents, test them, add tools, and even build multi-agent systems.

Build your own AI agent from scratch for free in 5 minutes

AI agents are among the most exciting areas of modern AI development. They are more powerful than simple chatbots because agents can use tools, run code, search the web, plan steps, and even work together with other agents to complete complex tasks.

In this article, I will show you how to build your first AI agent from scratch using Google’s ADK (Agent Development Kit). This is an open-source framework that makes it easier to create agents, test them, add tools, and even build multi-agent systems.

The best part? You can build everything for free and in just a few minutes if you already have Python installed.

Let’s get started.

What Is an AI Agent? (Simple Explanation)

Before we begin, let’s quickly review what an AI agent actually is.

A normal AI model (like Gemini or Gemini) only gives you text answers.
An AI agent is different — it can:

• Perform tasks, not just answer questions
• Use tools, such as Google Search, calculators, APIs, or databases
• Make decisions and plan steps
• Work autonomously with minimal human help

You can think of an AI agent as a small “AI worker” that can do tasks instead of you.

In this tutorial, we will build a simple agent first, then upgrade it into a multi-agent system with separate agents for research, summarizing, and coordination.

What You Need Before Starting

To follow this tutorial, you only need:

• Python installed on your computer
• Any code editor, such as VS Code (or Google Antigravity IDE if you want)
• Google ADK — the open-source framework we will install
• A Claude API key, which is free to generate

If you have everything ready, let’s build!

Build AI Agents From Scratch

Step 1: Create a Project Folder and Virtual Environment

First, open your terminal and create a folder: