agentscope-java

When the user asks you to write AgentScope Java code, follow these instructions carefully.

CRITICAL RULES - NEVER VIOLATE THESE

🚫 ABSOLUTELY FORBIDDEN:

1. NEVER use .block() in example code - This is the #1 mistake. Only use .block() in main() methods or test code when explicitly creating a runnable example.
2. NEVER use Thread.sleep() - Use Mono.delay() instead.
3. NEVER use ThreadLocal - Use Reactor Context with Mono.deferContextual().
4. NEVER hardcode API keys - Always use System.getenv().
5. NEVER ignore errors silently - Always log errors and provide fallback values.
6. NEVER use wrong import paths - All models are in io.agentscope.core.model.*, NOT io.agentscope.model.*.

✅ ALWAYS DO:

1. Use Mono and Flux for all asynchronous operations.
2. Chain operations with .map(), .flatMap(), .then().
3. Use Builder pattern for creating agents, models, and messages.
4. Include error handling with .onErrorResume() or .onErrorReturn().
5. Add logging with SLF4J for important operations.
6. Use correct imports: import io.agentscope.core.model.DashScopeChatModel;
7. Use correct APIs (many methods don't exist or have changed):
   • toolkit.registerTool() NOT registerObject()
   • toolkit.getToolNames() NOT getTools()
   • event.getToolUse().getName() NOT getToolName()
   • result.getOutput() NOT getContent() (ToolResultBlock)
   • event.getToolResult() NOT getResult() (PostActingEvent)
   • toolUse.getInput() NOT getArguments() (ToolUseBlock)
   • Model builder: NO temperature() method, use defaultOptions(GenerateOptions.builder()...)
   • Hook events: NO getMessages(), getResponse(), getIterationCount(), getThinkingBlock() methods
   • ToolResultBlock: NO getToolUseName() method, use event.getToolUse().getName() instead
   • ToolResultBlock.getOutput() returns List<ContentBlock> NOT String, need to convert
   • @ToolParam format: MUST use @ToolParam(name = "x", description = "y") NOT @ToolParam(name="x")

---

WHEN GENERATING CODE

FIRST: Identify the context

• Is this a main() method or test code? → .block() is allowed (but add a warning comment)
• Is this agent logic, service method, or library code? → .block() is FORBIDDEN

For every code example you provide:

1. Check: Does it use .block()? → If yes in non-main/non-test code, REWRITE IT.
2. Check: Are all operations non-blocking? → If no, FIX IT.
3. Check: Does it have error handling? → If no, ADD IT.
4. Check: Are API keys from environment? → If no, CHANGE IT.
5. Check: Are imports correct? → If using io.agentscope.model.*, FIX TO io.agentscope.core.model.*.

Default code structure for agent logic:

// ✅ CORRECT - Non-blocking, reactive (use this pattern by default)
return model.generate(messages, null, null)
    .map(response -> processResponse(response))
    .onErrorResume(e -> {
        log.error("Operation failed", e);
        return Mono.just(fallbackValue);
    });

// ❌ WRONG - Never generate this in agent logic
String result = model.generate(messages, null, null).block(); // DON'T DO THIS

Only for main() methods (add warning comment):

public static void main(String[] args) {
    // ⚠️ .block() is ONLY allowed here because this is a main() method
    Msg response = agent.call(userMsg).block();
    System.out.println(response.getTextContent());
}

---

PROJECT SETUP

When creating a new AgentScope project, use the correct Maven dependencies:

Maven Configuration (pom.xml)

For production use (recommended):

<properties>
    <java.version>17</java.version>
</properties>

<dependencies>
    <!-- Use the latest stable release from Maven Central -->
    <dependency>
        <groupId>io.agentscope</groupId>
        <artifactId>agentscope</artifactId>
        <version>1.0.5</version>
    </dependency>
</dependencies>

For local development (if working with source code):

<properties>
    <agentscope.version>1.0.5</agentscope.version>
    <java.version>17</java.version>
</properties>

<dependencies>
    <dependency>
        <groupId>io.agentscope</groupId>
        <artifactId>agentscope-core</artifactId>
        <version>${agentscope.version}</version>
    </dependency>
</dependencies>

⚠️ IMPORTANT: Version Selection

• Use agentscope:1.0.5 for production (stable, from Maven Central)
• Use agentscope-core:1.0.5 only if you're developing AgentScope itself
• NEVER use version 0.1.0-SNAPSHOT - this version doesn't exist

⚠️ CRITICAL: Common Dependency Mistakes

❌ WRONG - These artifacts don't exist:

<!-- DON'T use these - they don't exist -->
<dependency>
    <groupId>io.agentscope</groupId>
    <artifactId>agentscope-model-dashscope</artifactId>  <!-- ❌ WRONG -->
</dependency>
<dependency>
    <groupId>io.agentscope</groupId>
    <artifactId>agentscope-model-openai</artifactId>  <!-- ❌ WRONG -->
</dependency>

❌ WRONG - These versions don't exist:

<dependency>
    <groupId>io.agentscope</groupId>
    <artifactId>agentscope-core</artifactId>
    <version>0.1.0-SNAPSHOT</version>  <!-- ❌ WRONG - doesn't exist -->
</dependency>
<dependency>
    <groupId>io.agentscope</groupId>
    <artifactId>agentscope</artifactId>
    <version>0.1.0</version>  <!-- ❌ WRONG - doesn't exist -->
</dependency>

✅ CORRECT - Use the stable release:

<!-- For production: use the stable release from Maven Central -->
<dependency>
    <groupId>io.agentscope</groupId>
    <artifactId>agentscope</artifactId>
    <version>1.0.5</version>  <!-- ✅ CORRECT -->
</dependency>

Available Model Classes (all in agentscope-core)

// DashScope (Alibaba Cloud)
import io.agentscope.core.model.DashScopeChatModel;

// OpenAI
import io.agentscope.core.model.OpenAIChatModel;

// Gemini (Google)
import io.agentscope.core.model.GeminiChatModel;

// Anthropic (Claude)
import io.agentscope.core.model.AnthropicChatModel;

// Ollama (Local models)
import io.agentscope.core.model.OllamaChatModel;

Optional Extensions

<!-- Long-term memory with Mem0 -->
<dependency>
    <groupId>io.agentscope</groupId>
    <artifactId>agentscope-extensions-mem0</artifactId>
    <version>${agentscope.version}</version>
</dependency>

<!-- RAG with Dify -->
<dependency>
    <groupId>io.agentscope</groupId>
    <artifactId>agentscope-extensions-rag-dify</artifactId>
    <version>${agentscope.version}</version>
</dependency>

---

PROJECT OVERVIEW & ARCHITECTURE

AgentScope Java is a reactive, message-driven multi-agent framework built on Project Reactor and Java 17+.

Core Abstractions

• Agent: The fundamental unit of execution. Most agents extend AgentBase.
• Msg: The message object exchanged between agents.
• Memory: Stores conversation history (InMemoryMemory, LongTermMemory).
• Toolkit & AgentTool: Defines capabilities the agent can use.
• Model: Interfaces with LLMs (OpenAI, DashScope, Gemini, Anthropic, etc.).
• Hook: Intercepts and modifies agent execution at various lifecycle points.
• Pipeline: Orchestrates multiple agents in sequential or parallel patterns.

Reactive Nature

Almost all operations (agent calls, model inference, tool execution) return Mono<T> or Flux<T>.

Key Design Principles

1. Non-blocking: All I/O operations are asynchronous
2. Message-driven: Agents communicate via immutable Msg objects
3. Composable: Agents and pipelines can be nested and combined
4. Extensible: Hooks and custom tools allow deep customization

---

CODING STANDARDS & BEST PRACTICES

2.1 Java Version & Style

Target Java 17 (LTS) for maximum compatibility:

• Use Java 17 features (Records, Switch expressions, Pattern Matching for instanceof, var, Sealed classes)
• AVOID Java 21+ preview features (pattern matching in switch, record patterns)
• Follow standard Java conventions (PascalCase for classes, camelCase for methods/variables)
• Use Lombok where appropriate (@Data, @Builder for DTOs/Messages)
• Prefer immutability for data classes
• Use meaningful names that reflect domain concepts

⚠️ CRITICAL: Avoid Preview Features

// ❌ WRONG - Requires Java 21 with --enable-preview
return switch (event) {
    case PreReasoningEvent e -> Mono.just(e);  // Pattern matching in switch
    default -> Mono.just(event);
};

// ✅ CORRECT - Java 17 compatible
if (event instanceof PreReasoningEvent e) {  // Pattern matching for instanceof (Java 17)
    return Mono.just(event);
} else {
    return Mono.just(event);
}

2.2 Reactive Programming (Critical)

⚠️ NEVER BLOCK IN AGENT LOGIC

Blocking operations will break the reactive chain and cause performance issues.

Rules:

• ❌ Never use .block() in agent logic (only in main methods or tests)
• ✅ Use Mono for single results (e.g., agent.call())
• ✅ Use Flux for streaming responses (e.g., model.stream())
• ✅ Chain operations using .map(), .flatMap(), .then()
• ✅ Use Mono.defer() for lazy evaluation
• ✅ Use Mono.deferContextual() for reactive context access

Example:

// ❌ WRONG - Blocking
public Mono<String> processData(String input) {
    String result = externalService.call(input).block(); // DON'T DO THIS
    return Mono.just(result);
}

// ✅ CORRECT - Non-blocking
public Mono<String> processData(String input) {
    return externalService.call(input)
        .map(this::transform)
        .flatMap(this::validate);
}

2.3 Message Handling (Msg)

Create messages using the Builder pattern:

Msg userMsg = Msg.builder()
    .role(MsgRole.USER)
    .content(TextBlock.builder().text("Hello").build())
    .name("user")
    .build();

Content Blocks:

• TextBlock: For text content
• ThinkingBlock: For Chain of Thought (CoT) reasoning
• ToolUseBlock: For tool calls
• ToolResultBlock: For tool outputs

Helper Methods:

// Prefer safe helper methods
String text = msg.getTextContent();  // Safe, returns null if not found

// Avoid direct access
String text = msg.getContent().get(0).getText();  // May throw NPE

2.4 Implementing Agents

Extend AgentBase and implement doCall(List<Msg> msgs):

public class MyAgent extends AgentBase {
    private final Model model;
    private final Memory memory;
    
    public MyAgent(String name, Model model) {
        super(name, "A custom agent", true, List.of());
        this.model = model;
        this.memory = new InMemoryMemory();
    }

    @Override
    protected Mono<Msg> doCall(List<Msg> msgs) {
        // 1. Process inputs
        if (msgs != null) {
            msgs.forEach(memory::addMessage);
        }
        
        // 2. Call model or logic
        return model.generate(memory.getMessages(), null, null)
            .map(response -> Msg.builder()
                .name(getName())
                .role(MsgRole.ASSISTANT)
                .content(TextBlock.builder().text(response.getText()).build())
                .build());
    }
}

2.5 Tool Definition

Use @Tool annotation for function-based tools. Tools can return:

• String (synchronous)
• Mono<String> (asynchronous)
• Mono<ToolResultBlock> (for complex results)

⚠️ CRITICAL: @ToolParam Format

• ✅ CORRECT: @ToolParam(name = "city", description = "City name")
• ❌ WRONG: @ToolParam(name="city", description="...") (no spaces around =)
• ❌ WRONG: @ToolParam("city") (missing name= and description=)

Synchronous Tool Example:

public class WeatherTools {
    @Tool(description = "Get current weather for a city. Returns temperature and conditions.")
    public String getWeather(
            @ToolParam(name = "city", description = "City name, e.g., 'San Francisco'") 
            String city) {
        // Implementation
        return "Sunny, 25°C";
    }
}

Asynchronous Tool Example:

public class AsyncTools {
    private final WebClient webClient;
    
    @Tool(description = "Fetch data from trusted API endpoint")
    public Mono<String> fetchData(
            @ToolParam(name = "url", description = "API endpoint URL (must start with https://api.myservice.com)") 
            String url) {
        // SECURITY: Validate URL to prevent SSRF
        if (!url.startsWith("https://api.myservice.com")) {
            return Mono.just("Error: URL not allowed. Must start with https://api.myservice.com");
        }

        return webClient.get()
            .uri(url)
            .retrieve()
            .bodyToMono(String.class)
            .timeout(Duration.ofSeconds(10))
            .onErrorResume(e -> Mono.just("Error: " + e.getMessage()));
    }
}

Register with Toolkit:

Toolkit toolkit = new Toolkit();
toolkit.registerTool(new WeatherTools());
toolkit.registerTool(new AsyncTools());

---

HOOK SYSTEM

Hooks allow you to intercept and modify agent execution at various lifecycle points.

Hook Interface

public interface Hook {
    <T extends HookEvent> Mono<T> onEvent(T event);
    default int priority() { return 100; }  // Lower = higher priority
}

Common Hook Events

• PreReasoningEvent: Before LLM reasoning (modifiable)
• PostReasoningEvent: After LLM reasoning (modifiable)
• ReasoningChunkEvent: Streaming reasoning chunks (notification)
• PreActingEvent: Before tool execution (modifiable)
• PostActingEvent: After tool execution (modifiable)
• ActingChunkEvent: Streaming tool execution (notification)

Hook Example

Java 17+ compatible (recommended):

Hook loggingHook = new Hook() {
    @Override
    public <T extends HookEvent> Mono<T> onEvent(T event) {
        // Use if-instanceof instead of switch patterns (Java 17 compatible)
        if (event instanceof PreReasoningEvent e) {
            log.info("Reasoning with model: {}", e.getModelName());
            return Mono.just(event);
        } else if (event instanceof PreActingEvent e) {
            log.info("Calling tool: {}", e.getToolUse().getName());
            return Mono.just(event);
        } else if (event instanceof PostActingEvent e) {
            log.info("Tool {} completed", e.getToolUse().getName());
            return Mono.just(event);
        } else {
            return Mono.just(event);
        }
    }
    
    @Override
    public int priority() {
        return 500;  // Low priority (logging)
    }
};

ReActAgent agent = ReActAgent.builder()
    .name("Assistant")
    .model(model)
    .hook(loggingHook)
    .build();

Alternative: Traditional if-else (Java 17):

Hook loggingHook = new Hook() {
    @Override
    public <T extends HookEvent> Mono<T> onEvent(T event) {
        if (event instanceof PreReasoningEvent) {
            PreReasoningEvent e = (PreReasoningEvent) event;
            log.info("Reasoning with model: {}", e.getModelName());
        } else if (event instanceof PreActingEvent) {
            PreActingEvent e = (PreActingEvent) event;
            log.info("Calling tool: {}", e.getToolUse().getName());
        } else if (event instanceof PostActingEvent) {
            PostActingEvent e = (PostActingEvent) event;
            log.info("Tool {} completed", e.getToolUse().getName());
        }
        return Mono.just(event);
    }
    
    @Override
    public int priority() {
        return 500;
    }
};

Priority Guidelines:

• 0-50: Critical system hooks (auth, security)
• 51-100: High priority hooks (validation, preprocessing)
• 101-500: Normal priority hooks (business logic)
• 501-1000: Low priority hooks (logging, metrics)

---

PIPELINE PATTERNS

Pipelines orchestrate multiple agents in structured workflows.

Sequential Pipeline

Executes agents in sequence (output of one becomes input of next):

SequentialPipeline pipeline = SequentialPipeline.builder()
    .addAgent(researchAgent)
    .addAgent(summaryAgent)
    .addAgent(reviewAgent)
    .build();

Msg result = pipeline.execute(userInput).block();

Fanout Pipeline

Executes agents in parallel and aggregates results:

FanoutPipeline pipeline = FanoutPipeline.builder()
    .addAgent(agent1)
    .addAgent(agent2)
    .addAgent(agent3)
    .build();

Msg result = pipeline.execute(userInput).block();

When to Use:

• Sequential: When each agent depends on the previous agent's output
• Fanout: When agents can work independently and results need aggregation

---

MEMORY MANAGEMENT

In-Memory (Short-term)

Memory memory = new InMemoryMemory();

Long-Term Memory

// Configure long-term memory
LongTermMemory longTermMemory = Mem0LongTermMemory.builder()
    .apiKey(System.getenv("MEM0_API_KEY"))
    .userId("user_123")
    .build();

// Use with agent
ReActAgent agent = ReActAgent.builder()
    .name("Assistant")
    .model(model)
    .longTermMemory(longTermMemory)
    .longTermMemoryMode(LongTermMemoryMode.BOTH)  // STATIC_CONTROL, AGENTIC, or BOTH
    .build();

Memory Modes:

• STATIC_CONTROL: Framework automatically manages memory (via hooks)
• AGENTIC: Agent decides when to use memory (via tools)
• BOTH: Combines both approaches

---

MCP (MODEL CONTEXT PROTOCOL) INTEGRATION

AgentScope supports MCP for integrating external tools and resources.

// Create MCP client
// SECURITY: In production, use a specific version or a local binary to prevent supply chain attacks
McpClientWrapper mcpClient = McpClientBuilder.stdio()
    .command("npx")
    .args("-y", "@modelcontextprotocol/server-filesystem@0.6.2", "/path/to/files") // Always pin versions
    .build();

// Register with toolkit
Toolkit toolkit = new Toolkit();
toolkit.registration()
    .mcpClient(mcpClient)
    .enableTools(List.of("read_file", "write_file"))
    .apply();

// Use with agent
ReActAgent agent = ReActAgent.builder()
    .name("Assistant")
    .model(model)
    .toolkit(toolkit)
    .build();

---

TESTING

Unit Testing with StepVerifier

@Test
void testAgentCall() {
    Msg input = Msg.builder()
        .role(MsgRole.USER)
        .content(TextBlock.builder().text("Hello").build())
        .build();
    
    StepVerifier.create(agent.call(input))
        .assertNext(response -> {
            assertEquals(MsgRole.ASSISTANT, response.getRole());
            assertNotNull(response.getTextContent());
        })
        .verifyComplete();
}

Mocking External Dependencies

@Test
void testWithMockModel() {
    Model mockModel = mock(Model.class);
    when(mockModel.generate(any(), any(), any()))
        .thenReturn(Mono.just(ChatResponse.builder()
            .text("Mocked response")
            .build()));
    
    ReActAgent agent = ReActAgent.builder()
        .name("TestAgent")
        .model(mockModel)
        .build();
    
    // Test agent behavior
}

Testing Best Practices:

• Always test reactive chains with StepVerifier
• Mock external dependencies (models, APIs)
• Test error cases and edge conditions
• Verify that hooks are called correctly
• Test timeout and cancellation scenarios

---

CODE STYLE GUIDE

Logging

private static final Logger log = LoggerFactory.getLogger(MyClass.class);

// Use parameterized logging
log.info("Processing message from user: {}", userId);
log.error("Failed to call model: {}", modelName, exception);

Error Handling

// Prefer specific error messages
return Mono.error(new IllegalArgumentException(
    "Invalid model name: " + modelName + ". Expected one of: " + VALID_MODELS));

// Use onErrorResume for graceful degradation
return model.generate(msgs, null, null)
    .onErrorResume(e -> {
        log.error("Model call failed, using fallback", e);
        return Mono.just(fallbackResponse);
    });

Null Safety

// Use Optional for nullable returns
public Optional<AgentTool> findTool(String name) {
    return Optional.ofNullable(tools.get(name));
}

// Use Objects.requireNonNull for validation
public MyAgent(Model model) {
    this.model = Objects.requireNonNull(model, "Model cannot be null");
}

Comments

// Use Javadoc for public APIs
/**
 * Creates a new agent with the specified configuration.
 *
 * @param name The agent name (must be unique)
 * @param model The LLM model to use
 * @return Configured agent instance
 * @throws IllegalArgumentException if name is null or empty
 */
public static ReActAgent create(String name, Model model) {
    // Implementation
}

// Use inline comments sparingly, only for complex logic
// Calculate exponential backoff: 2^attempt * baseDelay
Duration delay = Duration.ofMillis((long) Math.pow(2, attempt) * baseDelayMs);

---

KEY LIBRARIES

• Reactor Core: Mono, Flux for reactive programming
• Jackson: JSON serialization/deserialization
• SLF4J: Logging (private static final Logger log = LoggerFactory.getLogger(MyClass.class);)
• OkHttp: HTTP client for model APIs
• MCP SDK: Model Context Protocol integration
• JUnit 5: Testing framework
• Mockito: Mocking framework
• Lombok: Boilerplate reduction

---

PROHIBITED PRACTICES

❌ NEVER Do These

1. Block in reactive chains

   // ❌ WRONG
   return someMonoOperation().block();
   

2. Use Thread.sleep() or blocking I/O

   // ❌ WRONG
   Thread.sleep(1000);
   
   // ✅ CORRECT
   return Mono.delay(Duration.ofSeconds(1));
   

3. Mutate shared state without synchronization

   // ❌ WRONG
   private List<Msg> messages = new ArrayList<>();
   public void addMessage(Msg msg) {
       messages.add(msg);  // Not thread-safe
   }
   

4. Ignore errors silently

   // ❌ WRONG
   .onErrorResume(e -> Mono.empty())
   
   // ✅ CORRECT
   .onErrorResume(e -> {
       log.error("Operation failed", e);
       return Mono.just(fallbackValue);
   })
   

5. Use ThreadLocal in reactive code

   // ❌ WRONG
   ThreadLocal<String> context = new ThreadLocal<>();
   
   // ✅ CORRECT
   return Mono.deferContextual(ctx -> {
       String value = ctx.get("key");
       // Use value
   });
   

6. Create agents without proper resource management

   // ❌ WRONG - No cleanup
   public void processRequests() {
       for (int i = 0; i < 1000; i++) {
           ReActAgent agent = createAgent();
           agent.call(msg).block();
       }
   }
   

7. Hardcode API keys or secrets

   // ❌ WRONG
   String apiKey = "sk-1234567890";
   
   // ✅ CORRECT
   String apiKey = System.getenv("OPENAI_API_KEY");
   

8. Use Java preview features (requires --enable-preview)

   // ❌ WRONG - Requires Java 21 with --enable-preview
   return switch (event) {
       case PreReasoningEvent e -> handleReasoning(e);
       case PostActingEvent e -> handleActing(e);
       default -> Mono.just(event);
   };
   
   // ✅ CORRECT - Java 17 compatible
   if (event instanceof PreReasoningEvent e) {
       return handleReasoning(e);
   } else if (event instanceof PostActingEvent e) {
       return handleActing(e);
   } else {
       return Mono.just(event);
   }
   

---

COMMON PITFALLS & SOLUTIONS

❌ Blocking Operations

// WRONG
Msg response = agent.call(msg).block();  // Don't block in agent logic

// CORRECT
return agent.call(msg)
    .flatMap(response -> processResponse(response));

❌ Null Handling

// WRONG
String text = msg.getContent().get(0).getText();  // May throw NPE

// CORRECT
String text = msg.getTextContent();  // Safe helper method
// OR
String text = msg.getContentBlocks(TextBlock.class).stream()
    .findFirst()
    .map(TextBlock::getText)
    .orElse("");

❌ Thread Context

// WRONG
ThreadLocal<String> context = new ThreadLocal<>();  // May not work in reactive streams

// CORRECT
return Mono.deferContextual(ctx -> {
    String value = ctx.get("key");
    // Use value
});

❌ Error Swallowing

// WRONG
.onErrorResume(e -> Mono.empty())  // Silent failure

// CORRECT
.onErrorResume(e -> {
    log.error("Failed to process: {}", input, e);
    return Mono.just(createErrorResponse(e));
})

---

COMPLETE EXAMPLE

package com.example.agentscope;

import io.agentscope.core.ReActAgent;
import io.agentscope.core.hook.Hook;
import io.agentscope.core.hook.HookEvent;
import io.agentscope.core.hook.ReasoningChunkEvent;
import io.agentscope.core.memory.InMemoryMemory;
import io.agentscope.core.message.Msg;
import io.agentscope.core.message.MsgRole;
import io.agentscope.core.message.TextBlock;
import io.agentscope.core.model.Model;
import io.agentscope.core.tool.Tool;
import io.agentscope.core.tool.ToolParam;
import io.agentscope.core.tool.Toolkit;
import io.agentscope.core.model.DashScopeChatModel;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import reactor.core.publisher.Mono;

import java.time.LocalDateTime;
import java.time.format.DateTimeFormatter;

/**
 * Complete example demonstrating AgentScope best practices.
 */
public class CompleteExample {
    
    private static final Logger log = LoggerFactory.getLogger(CompleteExample.class);
    
    public static void main(String[] args) {
        // 1. Create model (no .temperature() method, use defaultOptions)
        Model model = DashScopeChatModel.builder()
            .apiKey(System.getenv("DASHSCOPE_API_KEY"))
            .modelName("qwen-plus")
            .stream(true)
            .build();
        
        // 2. Create toolkit with tools
        Toolkit toolkit = new Toolkit();
        toolkit.registerTool(new WeatherTools());
        toolkit.registerTool(new TimeTools());
        
        // 3. Create hook for streaming output
        Hook streamingHook = new Hook() {
            @Override
            public <T extends HookEvent> Mono<T> onEvent(T event) {
                if (event instanceof ReasoningChunkEvent e) {
                    String text = e.getIncrementalChunk().getTextContent();
                    if (text != null) {
                        System.out.print(text);
                    }
                }
                return Mono.just(event);
            }
            
            @Override
            public int priority() {
                return 500;  // Low priority
            }
        };
        
        // 4. Build agent
        ReActAgent agent = ReActAgent.builder()
            .name("Assistant")
            .sysPrompt("You are a helpful assistant. Use tools when appropriate.")
            .model(model)
            .toolkit(toolkit)
            .memory(new InMemoryMemory())
            .hook(streamingHook)
            .maxIters(10)
            .build();
        
        // 5. Use agent
        Msg userMsg = Msg.builder()
            .role(MsgRole.USER)
            .content(TextBlock.builder()
                .text("What's the weather in San Francisco and what time is it?")
                .build())
            .build();
        
        try {
            System.out.println("User: " + userMsg.getTextContent());
            System.out.print("Assistant: ");
            
            // ⚠️ IMPORTANT: .block() is ONLY allowed in main() methods for demo purposes
            // NEVER use .block() in agent logic, service methods, or library code
            Msg response = agent.call(userMsg).block();
            
            System.out.println("\n\n--- Response Details ---");
            System.out.println("Role: " + response.getRole());
            System.out.println("Content: " + response.getTextContent());
            
        } catch (Exception e) {
            log.error("Error during agent execution", e);
            System.err.println("Error: " + e.getMessage());
        }
    }
    
    /**
     * Example tool class for weather information.
     */
    public static class WeatherTools {
        
        @Tool(description = "Get current weather for a city. Returns temperature and conditions.")
        public String getWeather(
                @ToolParam(name = "city", description = "City name, e.g., 'San Francisco'") 
                String city) {
            
            log.info("Getting weather for city: {}", city);
            
            // Simulate API call
            return String.format("Weather in %s: Sunny, 22°C, Light breeze", city);
        }
    }
    
    /**
     * Example tool class for time information.
     */
    public static class TimeTools {
        
        private static final DateTimeFormatter FORMATTER = 
            DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
        
        @Tool(description = "Get current date and time")
        public String getCurrentTime() {
            LocalDateTime now = LocalDateTime.now();
            String formatted = now.format(FORMATTER);
            
            log.info("Returning current time: {}", formatted);
            
            return "Current time: " + formatted;
        }
    }
}

---

QUICK REFERENCE

Agent Creation

ReActAgent agent = ReActAgent.builder()
    .name("AgentName")
    .sysPrompt("System prompt")
    .model(model)
    .toolkit(toolkit)
    .memory(memory)
    .hooks(hooks)
    .maxIters(10)
    .build();

Message Creation

Msg msg = Msg.builder()
    .role(MsgRole.USER)
    .content(TextBlock.builder().text("Hello").build())
    .build();

Tool Registration

Toolkit toolkit = new Toolkit();
toolkit.registerTool(new MyTools());

Hook Creation

Hook hook = new Hook() {
    public <T extends HookEvent> Mono<T> onEvent(T event) {
        // Handle event
        return Mono.just(event);
    }
};

Pipeline Creation

SequentialPipeline pipeline = SequentialPipeline.builder()
    .addAgent(agent1)
    .addAgent(agent2)
    .build();

---