Anthropic

Setup

import { AnthropicProvider } from "noumen";

const provider = new AnthropicProvider({
  apiKey: "sk-ant-...",
  model: "claude-sonnet-4-20250514", // default
});

Options

Streaming

The Anthropic provider uses the messages.stream() API. It internally maps Anthropic's event types to noumen's OpenAI-compatible chunk format:

• content_block_start / content_block_delta for text and tool calls
• message_start for initial token counts
• message_delta for final output token count
• message_stop for the finish signal with usage

Message conversion

Anthropic uses a different message format than OpenAI. The provider handles this automatically:

• System messages become the system parameter
• Tool results are wrapped in tool_result content blocks within user messages
• Tool calls use Anthropic's tool_use content block format

Models

• claude-sonnet-4-20250514 -- balanced speed and capability
• claude-opus-4-20250514 -- highest capability
• claude-haiku-3-20250307 -- fastest, most affordable