> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/run-llama/LlamaIndexTS/llms.txt
> Use this file to discover all available pages before exploring further.

# Anthropic

> Anthropic Claude LLM provider integration

## Overview

The Anthropic provider integrates Claude models with LlamaIndex.TS, supporting all Claude 3, 3.5, 3.7, and 4 series models.

## Installation

```bash theme={null}
npm install @llamaindex/anthropic
```

## Basic Usage

```typescript theme={null}
import { Anthropic } from "@llamaindex/anthropic";

const llm = new Anthropic({
  model: "claude-3-5-sonnet-20241022",
  temperature: 0.7
});

const response = await llm.chat({
  messages: [
    { role: "system", content: "You are a helpful assistant." },
    { role: "user", content: "Explain quantum computing" }
  ]
});

console.log(response.message.content);
```

## Constructor Options

<ParamField path="model" type="string" default="claude-3-opus">
  Claude model name
</ParamField>

<ParamField path="temperature" type="number" default={1}>
  Sampling temperature (0-1)
</ParamField>

<ParamField path="topP" type="number">
  Nucleus sampling parameter
</ParamField>

<ParamField path="maxTokens" type="number">
  Maximum tokens in response
</ParamField>

<ParamField path="apiKey" type="string">
  Anthropic API key (defaults to `ANTHROPIC_API_KEY` env variable)
</ParamField>

<ParamField path="maxRetries" type="number" default={10}>
  Maximum request retries
</ParamField>

<ParamField path="timeout" type="number" default={60000}>
  Request timeout in milliseconds
</ParamField>

<ParamField path="additionalChatOptions" type="AnthropicAdditionalChatOptions">
  Additional options like `thinking` mode
</ParamField>

## Supported Models

### Claude 4 (Latest)

* `claude-4-5-sonnet` / `claude-sonnet-4-5-20250929`
* `claude-4-1-opus` / `claude-opus-4-1-20250805`
* `claude-4-0-opus` / `claude-opus-4-20250514`
* `claude-4-0-sonnet` / `claude-sonnet-4-20250514`

### Claude 3.7

* `claude-3-7-sonnet` / `claude-3-7-sonnet-20250219`

### Claude 3.5

* `claude-3-5-sonnet-20241022`
* `claude-3-5-sonnet-20240620`
* `claude-3-5-haiku-20241022`

### Claude 3

* `claude-3-opus-20240229`
* `claude-3-sonnet-20240229`
* `claude-3-haiku-20240307`

All models support 200K context window.

## Streaming

```typescript theme={null}
const stream = await llm.chat({
  messages: [{ role: "user", content: "Write a short story" }],
  stream: true
});

for await (const chunk of stream) {
  process.stdout.write(chunk.delta);
}
```

## Function Calling

Claude 3+ models support tool use:

```typescript theme={null}
import { tool } from "@llamaindex/core/tools";
import { z } from "zod";

const weatherTool = tool({
  name: "get_weather",
  description: "Get weather for a location",
  parameters: z.object({
    location: z.string(),
    units: z.enum(["celsius", "fahrenheit"]).optional()
  }),
  execute: async ({ location, units = "celsius" }) => {
    return `Weather in ${location}: 22°${units === "celsius" ? "C" : "F"}`;
  }
});

const response = await llm.chat({
  messages: [{ role: "user", content: "What's the weather in London?" }],
  tools: [weatherTool]
});
```

## Extended Thinking

Claude 4+ supports extended thinking blocks:

```typescript theme={null}
const llm = new Anthropic({
  model: "claude-4-5-sonnet",
  additionalChatOptions: {
    thinking: "enabled"  // Enable thinking blocks
  }
});

const response = await llm.chat({
  messages: [{ role: "user", content: "Solve this complex problem..." }]
});

// Access thinking process
if (response.message.options?.thinking) {
  console.log("Thinking:", response.message.options.thinking);
  console.log("Signature:", response.message.options.thinking_signature);
}
```

## Multi-modal Input

### Images

```typescript theme={null}
const response = await llm.chat({
  messages: [
    {
      role: "user",
      content: [
        { type: "text", text: "Describe this image" },
        {
          type: "image",
          data: imageBase64,
          mimeType: "image/jpeg"  // or png, gif, webp
        }
      ]
    }
  ]
});
```

### PDFs

```typescript theme={null}
const response = await llm.chat({
  messages: [
    {
      role: "user",
      content: [
        { type: "text", text: "Summarize this PDF" },
        {
          type: "file",
          data: pdfBase64,
          mimeType: "application/pdf"
        }
      ]
    }
  ]
});
```

## Prompt Caching (Beta)

Use cache control to reduce costs for repeated content:

```typescript theme={null}
const response = await llm.chat({
  messages: [
    {
      role: "system",
      content: "You are an expert on this large document...",
      options: {
        cache_control: { type: "ephemeral" }
      }
    },
    { role: "user", content: "What does it say about topic X?" }
  ]
});
```

## Configuration

### Environment Variables

```bash theme={null}
ANTHROPIC_API_KEY=sk-ant-...
```

### Global Settings

```typescript theme={null}
import { Settings } from "llamaindex";
import { Anthropic } from "@llamaindex/anthropic";

Settings.llm = new Anthropic({
  model: "claude-3-5-sonnet-20241022"
});
```

## Response Format

Note: Anthropic does not support native structured output. Use tool calling for structured data:

```typescript theme={null}
const extractionTool = tool({
  name: "extract_info",
  description: "Extract structured information",
  parameters: z.object({
    name: z.string(),
    age: z.number(),
    email: z.string().email()
  }),
  execute: async (data) => data
});

const response = await llm.chat({
  messages: [{ role: "user", content: "Extract: John is 30, john@example.com" }],
  tools: [extractionTool]
});
```

## Message Handling

Claude has specific requirements:

### System Messages

System messages are handled separately:

```typescript theme={null}
const response = await llm.chat({
  messages: [
    { role: "system", content: "System prompt" },  // Extracted automatically
    { role: "user", content: "User message" },
    { role: "assistant", content: "Assistant response" },
    { role: "user", content: "Follow-up" }
  ]
});
```

### Message Alternation

Messages must alternate between user and assistant:

```typescript theme={null}
// ✅ Correct
[
  { role: "user", content: "Message 1" },
  { role: "assistant", content: "Response 1" },
  { role: "user", content: "Message 2" }
]

// ❌ Incorrect - consecutive user messages
[
  { role: "user", content: "Message 1" },
  { role: "user", content: "Message 2" }  // Will be merged automatically
]
```

The provider automatically merges consecutive messages.

## Model Capabilities

| Model      | Tool Use | Vision | PDFs | Thinking |
| ---------- | -------- | ------ | ---- | -------- |
| Claude 4   | ✅        | ✅      | ✅    | ✅        |
| Claude 3.7 | ✅        | ✅      | ✅    | ❌        |
| Claude 3.5 | ✅        | ✅      | ✅    | ❌        |
| Claude 3   | ✅        | ✅      | ✅    | ❌        |
| Claude 2   | ❌        | ❌      | ❌    | ❌        |

## Error Handling

```typescript theme={null}
try {
  const response = await llm.chat({ messages });
} catch (error) {
  if (error.status === 429) {
    console.error("Rate limit exceeded");
  } else if (error.status === 401) {
    console.error("Invalid API key");
  } else {
    console.error("Error:", error.message);
  }
}
```

## Best Practices

1. **Use latest models**: Claude 4.5 Sonnet offers best performance
2. **Enable thinking for complex tasks**: Improves reasoning quality
3. **Use cache control**: Reduce costs for repeated content
4. **Handle message alternation**: Provider handles this automatically
5. **Leverage vision**: Claude excels at image and PDF analysis
6. **Set appropriate maxTokens**: Default is 4096, adjust as needed

## See Also

* [Core LLM API](/api/core/llms)
* [Anthropic Documentation](https://docs.anthropic.com)