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Access 11 Anthropic models through Mastra's model router. Authentication is handled automatically using the ANTHROPIC_API_KEY environment variable.

Learn more in the Anthropic documentation.

ANTHROPIC_API_KEY=your-api-key
import { Agent } from "@mastra/core";

const agent = new Agent({
  name: "my-agent",
  instructions: "You are a helpful assistant",
  model: "anthropic/claude-3-5-haiku-20241022",
});

// Generate a response
const response = await agent.generate("Hello!");

// Stream a response
const stream = await agent.stream("Tell me a story");
for await (const chunk of stream) {
  console.log(chunk);
}

Models​

ModelImageAudioVideoToolsStreamingContext Window
anthropic/claude-3-5-sonnet-20241022✓✗✗✓✗200,000
anthropic/claude-3-5-sonnet-20240620✓✗✗✓✗200,000
anthropic/claude-3-opus-20240229✓✗✗✓✗200,000
anthropic/claude-sonnet-4-5-20250929✓✗✗✓✗200,000
anthropic/claude-sonnet-4-20250514✓✗✗✓✗200,000
anthropic/claude-opus-4-20250514✓✗✗✓✗200,000
anthropic/claude-3-5-haiku-20241022✓✗✗✓✗200,000
anthropic/claude-3-haiku-20240307✓✗✗✓✗200,000
anthropic/claude-3-7-sonnet-20250219✓✗✗✓✗200,000
anthropic/claude-opus-4-1-20250805✓✗✗✓✗200,000
anthropic/claude-3-sonnet-20240229✓✗✗✓✗200,000

Advanced Configuration​

Custom Headers​

const agent = new Agent({
  name: "custom-agent",
  model: {
    modelId: "claude-3-5-haiku-20241022",
    apiKey: process.env.ANTHROPIC_API_KEY,
    headers: {
      "X-Custom-Header": "value",
    },
  },
});

Dynamic Model Selection​

const agent = new Agent({
  name: "dynamic-agent",
  model: ({ runtimeContext }) => {
    const useAdvanced = runtimeContext.task === "complex";
    return useAdvanced
      ? "anthropic/claude-sonnet-4-5-20250929"
      : "anthropic/claude-3-5-haiku-20241022";
  },
});

Direct Provider Installation​

This provider can also be installed directly as a standalone package, which can be used instead of the Mastra model router string. View the package documentation for more details.

npm install @ai-sdk/anthropic