---
title: Claude Fable 5.1 | Runware Docs
url: https://runware.ai/docs/models/anthropic-claude-fable-5-1
description: Frontier multimodal model for long-running coding, research, and professional work
---
# Claude Fable 5.1

![Claude Fable 5.1](https://assets.runware.ai/covers/anthropic-claude-fable-5-1.jpg)

Claude Fable 5.1 is the next release in Anthropic’s Fable line, aimed at long-horizon coding, agentic execution, and multimodal research. It reads text and images, calls tools, and supports extended thinking, with a 1M-token context window and a 128K-token maximum output for work that has to hold an entire project in view. It fits document-heavy analysis, sustained agent runs, and engineering tasks that span many files.

- **Status**: compatible-only
- **ID**: `anthropic-claude-fable-5-1`
- **Context window**: 1M context
- **Max output**: 128K output
- **Creator**: Anthropic
- **Release Date**: September 1, 2026
- **Capabilities**: Text to Text, Image to Text, Checkpoint

**Claude Fable 5.1** is served through Runware's **compatible endpoints**, which take another provider's request format. Point the SDK you already use at Runware by changing the base URL and the API key, and set `model` to `anthropic:claude@fable-5.1`.

Requests and responses keep the provider's format, so **its reference documents every parameter**.

| Endpoint | Format |
| --- | --- |
| `/v1/chat/completions` | [OpenAI Chat Completions](https://runware.ai/docs/tools/compatible-apis#openai-chat-completions) |
| `/v1/messages` | [Anthropic Messages](https://runware.ai/docs/tools/compatible-apis#anthropic-messages) |

### [Chat Completions](https://runware.ai/docs/models/anthropic-claude-fable-5-1#chat-completions)

**cURL**:

```bash
curl -X POST https://api.runware.ai/v1/chat/completions \
  -H "Authorization: Bearer $RUNWARE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "anthropic:claude@fable-5.1",
    "messages": [{"role": "user", "content": "What is the capital of France?"}]
  }'
```

**Python**:

```python
from openai import OpenAI

client = OpenAI(
    api_key="your_runware_api_key",
    base_url="https://api.runware.ai/v1",
)

response = client.chat.completions.create(
    model="anthropic:claude@fable-5.1",
    messages=[{"role": "user", "content": "What is the capital of France?"}],
)

print(response.choices[0].message.content)
```

**TypeScript**:

```typescript
import OpenAI from 'openai';

const client = new OpenAI({
  apiKey: 'your_runware_api_key',
  baseURL: 'https://api.runware.ai/v1',
});

const response = await client.chat.completions.create({
  model: 'anthropic:claude@fable-5.1',
  messages: [{ role: 'user', content: 'What is the capital of France?' }],
});

console.log(response.choices[0].message.content);
```

[Compatible APIs](https://runware.ai/docs/tools/compatible-apis#openai-chat-completions) covers streaming, tool calling and how the endpoint differs from OpenAI, and the [OpenAI API reference](https://platform.openai.com/docs/api-reference/chat/create) lists every parameter.

### [Messages](https://runware.ai/docs/models/anthropic-claude-fable-5-1#messages)

**cURL**:

```bash
curl -X POST https://api.runware.ai/v1/messages \
  -H "Authorization: Bearer $RUNWARE_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "anthropic:claude@fable-5.1",
    "max_tokens": 1024,
    "messages": [{"role": "user", "content": "What is the capital of France?"}]
  }'
```

**Python**:

```python
from anthropic import Anthropic

client = Anthropic(
    auth_token="your_runware_api_key",
    base_url="https://api.runware.ai",
)

message = client.messages.create(
    model="anthropic:claude@fable-5.1",
    max_tokens=1024,
    messages=[{"role": "user", "content": "What is the capital of France?"}],
)

print(message.content[0].text)
```

**TypeScript**:

```typescript
import Anthropic from '@anthropic-ai/sdk';

const client = new Anthropic({
  authToken: 'your_runware_api_key',
  baseURL: 'https://api.runware.ai',
});

const message = await client.messages.create({
  model: 'anthropic:claude@fable-5.1',
  max_tokens: 1024,
  messages: [{ role: 'user', content: 'What is the capital of France?' }],
});

console.log(message.content[0].text);
```

[Compatible APIs](https://runware.ai/docs/tools/compatible-apis#anthropic-messages) covers how the Anthropic SDKs authenticate against Runware, and the [Claude API reference](https://platform.claude.com/docs/en/api/messages) lists every parameter.

## Cost and speed

**Rates** (per 1M tokens)

- Input: `$10.00`
- Output: `$50.00`
- Cached input: `$0.25`
- Cache write: `$12.50`

billed per token, so a request costs what the model produced · [How pricing works](https://runware.ai/docs/models-api/pricing)