How Google Builds AI Agents: Deep Dive into the New ADK Python Repo

Google's Agent Development Kit (ADK) provides a structured framework for building AI agents by organizing them like mini companies with distinct roles: a Brain (the agent making decisions), Hands (tools for execution), and a Manager (runner orchestrating operations). The Python repo demonstrates how to compose these components into cohesive, scalable AI systems that can handle complex tasks through tool integration and intelligent task delegation.

Key Points

• •ADK structures AI agents as organizational hierarchies with specialized roles (Brain, Hands, Manager) rather than monolithic systems
• •The Brain component handles decision-making and reasoning using language models
• •Tools (Hands) are modular, composable functions that agents can invoke to interact with external systems
• •The Runner (Manager) orchestrates execution flow, manages state, and coordinates between agent decisions and tool execution
• •Tool definitions must be explicit and well-documented for the agent to understand capabilities and constraints
• •ADK supports multi-step reasoning where agents can chain tool calls to accomplish complex objectives
• •The framework emphasizes separation of concerns—agent logic, tool implementation, and execution management are decoupled
• •Python implementation allows rapid prototyping and integration with existing ML/data science ecosystems
• •Error handling and tool result validation are built into the execution loop to ensure reliability
• •ADK enables scaling from single-agent systems to multi-agent architectures with shared tool libraries

Workflow Diagram

Concepts