ChatAnthropic

Wrapper around Anthropic Messages API (aka Claude API).

Setup

The Anthropic API uses API keys for authentication. Visit your API Keys page to retrieve the API key you'll use in your requests.

The following models are available:

• claude-3-5-sonnet-20240620
• claude-3-haiku-20240307
• claude-3-opus-20240229
• claude-3-sonnet-20240229
• claude-2.0
• claude-2.1

Mind that the list may not be up-to-date. See https://docs.anthropic.com/en/docs/about-claude/models for the updated list.

Usage

final apiKey = Platform.environment['ANTHROPIC_API_KEY'];

final chatModel = ChatAnthropic(
  apiKey: apiKey,
  defaultOptions: ChatAnthropicOptions(
    model: 'claude-3-5-sonnet-20240620',
    temperature: 0,
  ),
);

final chatPrompt = ChatPromptTemplate.fromTemplates([
  (ChatMessageType.system, 'You are a helpful assistant that translates {input_language} to {output_language}.'),
  (ChatMessageType.human, 'Text to translate:\n{text}'),
]);

final chain = chatPrompt | chatModel | StringOutputParser();

final res = await chain.invoke({
  'input_language': 'English',
  'output_language': 'French',
  'text': 'I love programming.',
});
print(res);
// -> 'J'adore programmer.'

Multimodal support

final apiKey = Platform.environment['ANTHROPIC_API_KEY'];

final chatModel = ChatAnthropic(
  apiKey: apiKey,
  defaultOptions: ChatAnthropicOptions(
    model: 'claude-3-5-sonnet-20240620',
    temperature: 0,
  ),
);

final res = await chatModel.invoke(
  PromptValue.chat([
    ChatMessage.human(
      ChatMessageContent.multiModal([
        ChatMessageContent.text('What fruit is this?'),
        ChatMessageContent.image(
          mimeType: 'image/jpeg',
          data: base64.encode(
            await File('./bin/assets/apple.jpeg').readAsBytes(),
          ),
        ),
      ]),
    ),
  ]),
);

print(res.output.content);
// -> 'The fruit in the image is an apple.'

Streaming

final apiKey = Platform.environment['ANTHROPIC_API_KEY'];

final promptTemplate = ChatPromptTemplate.fromTemplates([
  (ChatMessageType.system, 'You are a helpful assistant that replies only with numbers in order without any spaces or commas.'),
  (ChatMessageType.human, 'List the numbers from 1 to {max_num}'),
]);

final chatModel = ChatAnthropic(
  apiKey: apiKey,
  defaultOptions: ChatAnthropicOptions(
    model: 'claude-3-5-sonnet-20240620',
    temperature: 0,
  ),
);

final chain = promptTemplate.pipe(chatModel).pipe(const StringOutputParser());

final stream = chain.stream({'max_num': '30'});
await stream.forEach(print);
// 123
// 456789101
// 112131415161
// 718192021222
// 324252627282
// 930

Tool calling

ChatAnthropic supports tool calling.

Check the docs for more information on how to use tools.

Example:

const tool = ToolSpec(
  name: 'get_current_weather',
  description: 'Get the current weather in a given location',
  inputJsonSchema: {
    'type': 'object',
    'properties': {
      'location': {
        'type': 'string',
        'description': 'The city and country, e.g. San Francisco, US',
      },
    },
    'required': ['location'],
  },
);
final chatModel = ChatAnthropic(
  apiKey: apiKey,
  defaultOptions: ChatAnthropicOptions(
    model: 'claude-3-5-sonnet-20240620',
    temperature: 0,
    tools: [tool],
  ),
);

final res = await model.invoke(
  PromptValue.string('What’s the weather like in Boston and Madrid right now in celsius?'),
);