Developer’s guide to multi-agent patterns in ADK

This guide introduces 8 essential multi-agent design patterns using Google's Agent Development Kit (ADK) for building production-grade AI systems.

• •Sequential Pipeline chains agents linearly using output_key to pass shared session state between steps (e.g., Parser → Extractor → Summarizer)
• •Coordinator/Dispatcher uses a central LlmAgent with AutoFlow to route user requests to specialist sub-agents based on intent
• •Parallel Fan-Out/Gather runs multiple agents simultaneously via ParallelAgent, then aggregates results through a synthesizer agent
• •Hierarchical Decomposition wraps sub-agent workflows as tools using AgentTool, allowing parent agents to delegate complex sub-tasks
• •Generator/Critic pattern uses a LoopAgent with a conditional exit condition to iteratively refine output until a quality gate is passed