---
title: "Claude Fable 5.1"
description: "Claude Fable 5.1 by Anthropic: 1M context. Compare provider prices and applicable pricing conditions on the model page. Pay as you go."
canonical: https://pirouter.ai/models/anthropic/claude-fable-5.1
last-updated: 2026-10-15
---

# Claude Fable 5.1

> Claude Fable 5.1 by Anthropic: 1M context. Compare provider prices and applicable pricing conditions on the model page. Pay as you go.

Claude Fable 5.1 is Anthropic's model for the most demanding reasoning and long-horizon agentic work, above Opus 5.5 in the Claude lineup. It suits long-running agentic coding, multistep research, and document and spreadsheet work, with a 1M-token context.

## At a glance

- Model ID: `anthropic/claude-fable-5.1`
- Also accepted as: `claude-fable-5-1`, `claude-fable-5.1`
- Vendor: Anthropic
- Category: text
- Openness: Proprietary
- Model page: https://platform.claude.com/docs/en/models/fable-5-1/overview
- Context: 1,000,000 tokens
- Max output: 128,000 tokens
- Added to pirouter: 2026-08-31
- Knowledge cutoff: 2026-06-01
- Status: Available

## Pricing (USD per 1M tokens)

|  | Input | Output | Cache read | Cache write | Cache write (1h) | Reasoning |
|---|---|---|---|---|---|---|
| Standard | $10 | $50 | $0.25 | $12.5 | $20 | $50 |

## Capabilities

- Function calling
- Tool choice
- Parallel tool calls
- Reasoning
- Prompt caching
- System messages
- Streaming
- Vision
- PDF input

## Reasoning effort

- max, xhigh, high, medium, low (default: high)

## How to call it

One pirouter API key works with every API format below; create it in the console. Use one of these formats; formats not listed are not available for this model.

- API key: https://app.pirouter.ai/sign-in

### OpenAI Responses

- Endpoint: `POST /v1/responses` on https://api.pirouter.ai
- Auth: `Authorization: Bearer <key>`
- SDK base URL: https://api.pirouter.ai/v1
- Reference: https://pirouter.ai/docs/api/responses

```bash
curl https://api.pirouter.ai/v1/responses \
  -H "Authorization: Bearer $PIROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "anthropic/claude-fable-5.1",
    "input": "Hello!"
  }'
```

### OpenAI Chat

- Endpoint: `POST /v1/chat/completions` on https://api.pirouter.ai
- Auth: `Authorization: Bearer <key>`
- SDK base URL: https://api.pirouter.ai/v1
- Reference: https://pirouter.ai/docs/api/chat-completions

```bash
curl https://api.pirouter.ai/v1/chat/completions \
  -H "Authorization: Bearer $PIROUTER_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "anthropic/claude-fable-5.1",
    "messages": [{ "role": "user", "content": "Hello!" }]
  }'
```

### Anthropic Messages

- Endpoint: `POST /v1/messages` on https://api.pirouter.ai
- Auth: `x-api-key: <key>`
- SDK base URL: https://api.pirouter.ai
- Reference: https://pirouter.ai/docs/api/messages

```bash
curl https://api.pirouter.ai/v1/messages \
  -H "x-api-key: $PIROUTER_API_KEY" \
  -H "anthropic-version: 2023-06-01" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "anthropic/claude-fable-5.1",
    "max_tokens": 1024,
    "messages": [{ "role": "user", "content": "Hello!" }]
  }'
```

## Providers

One row per provider; pirouter sends each request to a healthy one.

| Provider | API format | Context | Max output | Input /M | Output /M | Trains on your data | Data retention |
|---|---|---|---|---|---|---|---|
| anthropic | openai, anthropic | 1,000,000 | 128,000 | $10 | $50 | No | Limited |

## Rankings

Where this model ranks on each blind-vote leaderboard, listing the boards where it makes the top 100. Open a board for the full ranking.

| Board | Rank | Score |
|---|---|---|
| [Overall](https://pirouter.ai/rankings/overall) | #6 / 385 | 1501 |
| [Coding](https://pirouter.ai/rankings/coding) | #15 / 380 | 1533 |
| [Math](https://pirouter.ai/rankings/math) | #4 / 371 | 1518 |
| [Creative writing](https://pirouter.ai/rankings/creative) | #9 / 383 | 1482 |
| [Instruction following](https://pirouter.ai/rankings/instruct) | #6 / 385 | 1498 |
| [Multi-turn](https://pirouter.ai/rankings/multiturn) | #22 / 383 | 1487 |
| [Long prompts](https://pirouter.ai/rankings/longctx) | #6 / 363 | 1511 |
| [Chinese](https://pirouter.ai/rankings/chinese) | #2 / 362 | 1573 |
| [Web dev](https://pirouter.ai/rankings/webdev) | #5 / 121 | 1749 |
| [Agents](https://pirouter.ai/rankings/agent) | #1 / 44 | +14.6 pp |
| [Vision](https://pirouter.ai/rankings/vision) | #12 / 144 | 1287 |
| [Documents](https://pirouter.ai/rankings/document) | #4 / 38 | 1493 |

Data: [LMArena leaderboard dataset](https://huggingface.co/datasets/lmarena-ai/leaderboard-dataset), used under [CC BY 4.0](https://creativecommons.org/licenses/by/4.0/) · Updated 2026-10-01

## Supported parameters

`tools`, `tool_choice`, `parallel_tool_calls`, `max_tokens`, `stop`, `reasoning`, `include_reasoning`, `stream`

## Links

- HTML: https://pirouter.ai/models/anthropic/claude-fable-5.1
- JSON: https://pirouter.ai/api/models/anthropic/claude-fable-5.1
- Providers JSON: https://api.pirouter.ai/v1/models/anthropic/claude-fable-5.1/endpoints
- Leaderboard ranks (JSON): https://pirouter.ai/api/models/anthropic/claude-fable-5.1/rankings
- Catalog: https://pirouter.ai/models
- Quickstart: https://pirouter.ai/docs/quickstart
- How routing works: https://pirouter.ai/docs/routing
- llms.txt: https://pirouter.ai/llms.txt

---

HTML version: https://pirouter.ai/models/anthropic/claude-fable-5.1 · Machine-readable index: https://pirouter.ai/llms.txt