Google ADK Framework

The Agent Development Kit (ADK 2.0)

Google ADK (Agent Development Kit) 2.0 went GA on May 19, 2026 at Google I/O. It is an open-source framework for building, orchestrating, and deploying AI agents. ADK 2.0 now supports Python, TypeScript, Go, Java, and Kotlin (including Android/Gemini Nano support for on-device agents).

ADK 2.0 vs Other Frameworks

What's New in ADK 2.0

• Graph-based Workflow Runtime: First-class support for routing, branching, iterative loops, fan-out/fan-in, and native human-in-the-loop (HITL) — bringing LangGraph-level graph control into ADK.
• Agent-as-a-Tool: Coordinator agents delegate sub-tasks to specialized subagents using them as callable tools — enabling deep hierarchical architectures.
• Multi-Language SDK: Python, TypeScript, Go, Java, and Kotlin (with Gemini Nano on-device support for Android).
• Enhanced State & Memory: Session persistence via Vertex AI and Firestore, with Session Rewind for time-travel debugging.
• Visual Agent Builder: Drag-and-drop UI for composing agent hierarchies and testing in real-time.
• Flexible Deployment: From local CLI/Web UI for development to Cloud Run, GKE, or custom infrastructure for production.
• Code Execution Sandbox: Safely execute agent-generated code via Vertex AI sandbox.
• Multi-Provider Models: Use Gemini, Claude, or GPT as the reasoning engine.

ADK Agent Definition (Python)

from google.adk import Agent, Tool

# Define tools
search_tool = Tool(
    name="search_knowledge_base",
    description="Search internal docs",
    function=search_kb_function
)

# Create agent
agent = Agent(
    name="support_agent",
    model="gemini-3.5-flash",
    tools=[search_tool],
    instruction="You are a helpful support agent...",
    sub_agents=[billing_agent, shipping_agent]  # Hierarchy!
)

# Run
response = agent.run("What is the refund policy?")