Overview

What is Eino ADK?

Eino ADK is an Agent development framework for Go, providing:

• ChatModelAgent: A ReAct Agent using LLM as the decision-maker, supporting tool calls, autonomous reasoning, and runtime enhancement (Middleware)
• Workflow Agents: Deterministic orchestration primitives (Sequential / Loop / Parallel)
• Runner / TurnLoop: Agent execution entry point, supporting event streams, checkpoint/resume, and multi-turn preemption
• Multi-Agent Collaboration: AgentAsTool (recommended), Workflow composition

Broadly applicable, model-agnostic, and deployment-agnostic.

ADK Architecture

Agent Interface

All ADK functionality revolves around the Agent interface:

type Agent interface {
    Name(ctx context.Context) string
    Description(ctx context.Context) string
    Run(ctx context.Context, input *AgentInput, options ...AgentRunOption) *AsyncIterator[*AgentEvent]
}

Semantics of Run:

1. Obtains task information from AgentInput and Context
2. Executes the task asynchronously, writing produced events to AsyncIterator
3. Returns the Iterator immediately after starting the async task (Future pattern)

ChatModelAgent

The core implementation of ADK. Uses ChatModel as the decision-maker and autonomously progresses problem solving through a ReAct Loop.

ChatModelAgent = ChatModel + Tools + ReAct Loop + Middleware

See details at: Eino ADK: ChatModelAgent Introduction

Multi-Agent Collaboration

💡 Recommended approach: AgentAsTool — Convert a sub-Agent into a Tool, and the parent Agent invokes it via ToolCall and receives the result. This is the most flexible and composable collaboration pattern.

See: Agent Collaboration

Runner

Runner is the execution entry point for Agents. The following features are only available when executing through Runner:

• Event stream output: Query/Run → AsyncIterator[AgentEvent]
• Checkpoint / Resume: Persist running state, support interrupt recovery
• TurnLoop: Multi-turn runtime, Push/Preempt/Stop

runner := adk.NewRunner(ctx, adk.RunnerConfig{
    Agent:           agent,
    EnableStreaming: true,
    CheckPointStore: store, // Optional
})

iter := runner.Query(ctx, "Your question")

See: Agent Runner and Extension | Agent Cancel and TurnLoop