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Eino ADK agent construction, middleware, and runner. Use when a user needs to build an AI Agent, configure ChatModelAgent with ReAct pattern, use middleware (filesystem, tool search, tool reduction, summarization, plan-task, skill), set up the Runner for event-driven execution, implement human-in-the-loop with interrupt/resume, or wrap agents as tools. Covers ChatModelAgent and DeepAgents.
npx skill4agent add cloudwego/eino-ext eino-agentgithub.com/cloudwego/eino/adktype Agent interface {
Name(ctx context.Context) string
Description(ctx context.Context) string
Run(ctx context.Context, input *AgentInput, opts ...AgentRunOption) *AsyncIterator[*AgentEvent]
}| Type | Description | Decision |
|---|---|---|
| ChatModelAgent | ReAct pattern: LLM reasons, calls tools, loops until done | Dynamic (LLM) |
| DeepAgent | Pre-built agent with planning, filesystem, sub-agents | Dynamic (LLM) |
| Custom Agent | Implement the Agent interface directly | Custom |
import (
"context"
"fmt"
"log"
"github.com/cloudwego/eino-ext/components/model/openai"
"github.com/cloudwego/eino/adk"
"github.com/cloudwego/eino/components/tool"
"github.com/cloudwego/eino/components/tool/utils"
"github.com/cloudwego/eino/compose"
)
func main() {
ctx := context.Background()
// 1. Create a tool
searchTool, _ := utils.InferTool("search_book", "Search books by genre",
func(ctx context.Context, input *struct {
Genre string `json:"genre" jsonschema_description:"Book genre"`
}) (string, error) {
return `{"books": ["The Great Gatsby"]}`, nil
})
// 2. Create model
cm, _ := openai.NewChatModel(ctx, &openai.ChatModelConfig{
APIKey: "your-key", Model: "gpt-4o",
})
// 3. Create agent
agent, _ := adk.NewChatModelAgent(ctx, &adk.ChatModelAgentConfig{
Name: "BookRecommender",
Description: "Recommends books",
Instruction: "You recommend books using the search_book tool.",
Model: cm,
ToolsConfig: adk.ToolsConfig{
ToolsNodeConfig: compose.ToolsNodeConfig{
Tools: []tool.BaseTool{searchTool},
},
},
})
// 4. Run with Runner
runner := adk.NewRunner(ctx, adk.RunnerConfig{Agent: agent})
iter := runner.Query(ctx, "recommend a fiction book")
for {
event, ok := iter.Next()
if !ok {
break
}
if event.Err != nil {
log.Fatal(event.Err)
}
msg, _ := event.Output.MessageOutput.GetMessage()
fmt.Printf("Agent[%s]: %v\n", event.AgentName, msg)
}
}runner := adk.NewRunner(ctx, adk.RunnerConfig{
Agent: myAgent,
EnableStreaming: true,
CheckPointStore: myStore, // for interrupt/resume
})
// Query (convenience for single user message)
iter := runner.Query(ctx, "hello")
// Run (full control over input messages)
iter := runner.Run(ctx, []adk.Message{schema.UserMessage("hello")})Handlersagent, _ := adk.NewChatModelAgent(ctx, &adk.ChatModelAgentConfig{
// ...
Handlers: []adk.ChatModelAgentMiddleware{fsMiddleware, summarizationMW},
})| Middleware | Package | Purpose |
|---|---|---|
| FileSystem | | File ops (read/write/edit/glob/grep) + shell |
| ToolSearch | | Dynamic tool selection via regex search |
| ToolReduction | | Truncate/clear large tool results |
| Summarization | | Compress long conversation history |
| PlanTask | | Task creation and progress tracking |
| Skill | | Skill-based progressive disclosure |
| PatchToolCalls | | Fix dangling tool calls in history |
subAgent := createMySubAgent()
agentTool := adk.NewAgentTool(ctx, subAgent)
parentAgent, _ := adk.NewChatModelAgent(ctx, &adk.ChatModelAgentConfig{
ToolsConfig: adk.ToolsConfig{
ToolsNodeConfig: compose.ToolsNodeConfig{
Tools: []tool.BaseTool{agentTool},
},
},
})compose.NewInterruptAndRerunErr(info)runner.ResumeWithParams(ctx, checkpointID, params)ChatModelAgentRunneragent.Run()DeepAgentadk/prebuilt/deepAgentAsTool