Building Custom Tools for Google ADK Agents

Wed, 21 Jan 2026 00:00:00 +0000

Give your AI agent superpowers with custom tools

Series Navigation: This is Post 3 of the Google ADK Tutorial Series. ← Previous: LiteLLM Integration: Making Your ADK Agents Model-Agnostic

What You’ll Learn

By the end of this post, you’ll understand the three types of tools in ADK:

Built-in Tools - Pre-built tools like Google Search that provide instant capabilities
Custom Function Tools - Your own Python functions that the agent can call
Agent as a Tool - Using other agents as callable tools for complex workflows

We’ll build a travel assistant agent that demonstrates all three tool types working together.

Fri, 16 Jan 2026 00:00:00 +0000

Switch between OpenAI, Claude, and Gemini with one line of code

📚 Series Navigation: This is Post 2 of the Google ADK Tutorial Series.
← Previous: Introduction to Google ADK

By the end of this post, you’ll:

Code on GitHub: The complete working example from this post is available at google-adk-samples/model_agnostic_agent