anthropic

Genkit Anthropic Sample

This sample demonstrates basic integration with Anthropic Claude models using Genkit Java.

Features Demonstrated

• Anthropic Plugin Setup - Configure Genkit with Claude models
• Flow Definitions - Create observable, traceable AI workflows
• Tool Usage - Define and use tools with automatic execution (Claude 3+)
• Text Generation - Generate text with Claude 4.5 Sonnet and Haiku
• Streaming - Real-time response streaming
• Code Generation - Generate code with Claude
• Creative Writing - Generate creative content with streaming

Supported Models

The Anthropic plugin supports the following Claude models:

Claude 4.5 Family

• claude-opus-4-5-20251101 - Most capable model, best for complex tasks
• claude-sonnet-4-5-20250929 - Excellent balance of capability and speed
• claude-haiku-4-5-20251001 - Fast and efficient

Claude 4 Family

• claude-opus-4-1-20250805 - Claude 4.1 Opus
• claude-opus-4-20250514 - Claude 4 Opus
• claude-sonnet-4-20250514 - Claude 4 Sonnet

Claude 3 Family

• claude-3-7-sonnet-20250219 - Claude 3.7 Sonnet
• claude-3-5-haiku-20241022 - Claude 3.5 Haiku
• claude-3-opus-20240229 - Most powerful Claude 3 model
• claude-3-haiku-20240307 - Fastest Claude 3 model

Prerequisites

• Java 21+
• Maven 3.6+
• Anthropic API key (get one at https://console.anthropic.com/)

Running the Sample

Option 1: Direct Run

# Set your Anthropic API key
export ANTHROPIC_API_KEY=your-api-key-here

# Navigate to the sample directory
cd java/samples/anthropic

# Run the sample
./run.sh
# Or: mvn compile exec:java

Option 2: With Genkit Dev UI (Recommended)

# Set your Anthropic API key
export ANTHROPIC_API_KEY=your-api-key-here

# Navigate to the sample directory
cd java/samples/anthropic

# Run with Genkit CLI
genkit start -- ./run.sh

The Dev UI will be available at http://localhost:4000

Available Flows

Flow	Model	Input	Output	Description
greeting	-	String (name)	String	Simple greeting flow
tellJoke	claude-sonnet-4-5	String (topic)	String	Generate a joke about a topic
chat	claude-sonnet-4-5	String (message)	String	Chat with Claude
weatherAssistant	claude-sonnet-4-5	String (query)	String	Weather assistant using tools
streamingChat	claude-sonnet-4-5	String (message)	String	Streaming chat responses
streamingWeather	claude-sonnet-4-5	String (query)	String	Streaming with tools
generateCode	claude-sonnet-4-5	String (prompt)	String	Code generation
creativeWriting	claude-sonnet-4-5	String (prompt)	String	Creative writing with streaming
summarize	claude-haiku-4-5	String (text)	String	Text summarization

Example API Calls

Once the server is running on port 8080:

Simple Greeting

curl -X POST http://localhost:8080/api/flows/greeting \
  -H 'Content-Type: application/json' \
  -d '"World"'

Generate a Joke

curl -X POST http://localhost:8080/api/flows/tellJoke \
  -H 'Content-Type: application/json' \
  -d '"programming"'

Chat with Claude

curl -X POST http://localhost:8080/api/flows/chat \
  -H 'Content-Type: application/json' \
  -d '"What makes Claude different from other AI assistants?"'

Weather Assistant (with tools)

curl -X POST http://localhost:8080/api/flows/weatherAssistant \
  -H 'Content-Type: application/json' \
  -d '"What is the weather in San Francisco?"'

Streaming Chat

curl -X POST http://localhost:8080/api/flows/streamingChat \
  -H 'Content-Type: application/json' \
  -d '"Explain quantum computing in simple terms"'

Code Generation

curl -X POST http://localhost:8080/api/flows/generateCode \
  -H 'Content-Type: application/json' \
  -d '"Write a Python function to find all prime numbers up to n using the Sieve of Eratosthenes"'

Creative Writing

curl -X POST http://localhost:8080/api/flows/creativeWriting \
  -H 'Content-Type: application/json' \
  -d '"Write a short story about a robot learning to paint"'

Summarization

curl -X POST http://localhost:8080/api/flows/summarize \
  -H 'Content-Type: application/json' \
  -d '"The quick brown fox jumps over the lazy dog. This sentence contains every letter of the English alphabet and is often used for typing practice and font displays."'

Configuration

The Anthropic plugin can be configured with the following options:

AnthropicPlugin plugin = new AnthropicPlugin(
    AnthropicPluginOptions.builder()
        .apiKey("your-api-key")           // Or use ANTHROPIC_API_KEY env var
        .baseUrl("https://api.anthropic.com/v1")  // Custom base URL
        .anthropicVersion("2023-06-01")   // API version
        .timeout(120)                     // Request timeout in seconds
        .build()
);

Features

Tool Usage

Claude 3+ models support function calling (tools). Define tools and let Claude decide when to use them:

Tool<Map<String, Object>, Map<String, Object>> weatherTool = genkit.defineTool(
    "getWeather",
    "Gets the current weather for a location",
    schema,
    inputClass,
    (ctx, input) -> {
        // Tool implementation
        return result;
    });

genkit.generate(
    GenerateOptions.builder()
        .model("anthropic/claude-sonnet-4-5-20250929")
        .prompt("What's the weather in Paris?")
        .tools(List.of(weatherTool))
        .build());

Streaming

Stream responses for real-time output:

genkit.generateStream(
    GenerateOptions.builder()
        .model("anthropic/claude-sonnet-4-5-20250929")
        .prompt("Tell me a story")
        .build(),
    (chunk) -> {
        System.out.print(chunk.getText());
    });

Vision (Claude 3+)

Claude 3+ models support image input:

Message userMessage = new Message();
userMessage.setRole(Role.USER);
userMessage.setContent(List.of(
    Part.text("What's in this image?"),
    Part.media("image/jpeg", imageUrl)
));

genkit.generate(
    GenerateOptions.builder()
        .model("anthropic/claude-sonnet-4-5-20250929")
        .messages(List.of(userMessage))
        .build());

Pricing

See Anthropic's pricing page for current model pricing.