Google Agent Development Kit (ADK)#
Summary#
ADK is Google’s open-source, model-agnostic framework for building AI agents. Available in Python, TypeScript, Go, and Java — the broadest language support of any agent framework. Features deterministic workflow agents (Sequential/Parallel/Loop), native A2A protocol for cross-framework interop, and native MCP for tools.
Key Takeaways#
- Four languages: Python, TypeScript, Go, Java — all first-class. Unique in the space.
- Model-agnostic: Supports Gemini, Claude, Ollama, vLLM, LiteLLM despite Google origin.
- Workflow agents: SequentialAgent, ParallelAgent, LoopAgent provide deterministic orchestration without LLM overhead. These are the ADK equivalent of langgraph-agent-orchestration’s graph nodes.
- Three interaction mechanisms: Shared session state, LLM-driven delegation (transfer_to_agent), and explicit invocation (AgentTool wrapping).
- Native A2A: First-class Agent-to-Agent protocol support — expose ADK agents as A2A services or consume external A2A agents.
- Native MCP: Full Model Context Protocol support for tool integration.
- ADK 2.0 Beta: Adding graph-based workflows, collaborative agents, and dynamic workflows — validating the multi-agent-orchestration graph convergence thesis.
- Built-in evaluation: Multi-turn eval datasets, local evaluation via CLI/UI. Most frameworks lack this.
- Deployment: Cloud Run, GKE, Agent Runtime, Ambient Agents.
Architecture#
Hierarchical agent composition:
- Parent-child via sub_agents (single parent rule)
- Workflow agents as deterministic orchestrators
- LlmAgent for reasoning tasks
- Custom agents (BaseAgent) for specialized logic
Multi-Agent Patterns#
- Coordinator/Dispatcher — central router
- Sequential Pipeline — ordered steps via state
- Parallel Fan-Out/Gather — concurrent execution
- Hierarchical Task Decomposition — recursive delegation
- Review/Critique (Generator-Critic) — quality loops
- Iterative Refinement — LoopAgent with escalation
- Human-in-the-Loop — PolicyEngine + SecurityPlugin
Positioning#
| Dimension | Google ADK |
|---|---|
| Model support | 10+ (Gemini, Claude, Ollama, vLLM, LiteLLM, etc.) |
| Languages | Python, TypeScript, Go, Java |
| Orchestration | Workflow agents + LLM transfer + AgentTool |
| State | Session state + long-term memory service |
| Interop | MCP (tools) + A2A (agents) |
| Production features | Eval, observability, deployment, streaming |
| Graph workflows | ADK 2.0 beta |
See Also#
- multi-agent-orchestration
- microsoft-agent-framework — similar scope, different ecosystem
- langgraph-agent-orchestration — graph-first alternative
- openai-agents-sdk — simpler but model-locked
- mcp-protocol