Claude Fable 5.1: AI Large Taal Models

Generate text with Claude Fable 5.1. Anthropic's flagship model with adaptive thinking, 1M context. Try free — pay per generation, no subscription.

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Overview

About this model

Claude Fable 5.1 is Anthropic's newest flagship model, built for long-horizon agentic coding, multistep research, and document, spreadsheet, and slide work. It runs with adaptive extended thinking always enabled (steerable via effort, from low up to max) and a 1 million token context window with up to 128K tokens of output. It accepts both text and image inputs — charts, tables, PDFs, and screenshots — for multimodal analysis, and is a step up in reasoning depth from the earlier Claude Fable 5. Pricing is token-based: $10.00 per million input tokens and $50.00 per million output tokens.

1Agentic Coding: Plan and execute long-horizon coding tasks that span many files, tools, and steps without losing track of the goal.
2Multistep Research: Chain together searches, document reads, and analysis across a 1M-token context without re-summarizing earlier steps.
3Document & Spreadsheet Work: Read and reason over long PDFs, spreadsheets, and slide decks, including scanned pages and screenshots.
4Scientific Analysis: Work through multi-step scientific or technical problems that benefit from always-on extended thinking.
5Multimodal Analysis: Combine image and text inputs to extract insights from charts, tables, diagrams, and screenshots.
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Pricing & Value

Cost analysis

muapiapp$10.00/M 输入 Token, $50.00/M 输出 Token

Token-based billing at Anthropic's official published rate. Minimum $0.0008 per call.

Fal.aiNiet beschikbaar

Claude Fable 5.1 is 不可用 on Fal.ai.

ReplicateNiet beschikbaar

Claude Fable 5.1 is 不可用 on Replicate.

** Competitor pricing is estimated based on similar model architectures and usage tiers.

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Technical Details

Configuration schema

Promptstring

用户消息或指令。

Default ValueExplain quantum entanglement in simple terms.
Afbeelding URLstring

多模态请求的可选图像 URL。

Default Valueundefined
系统Promptstring

可选的系统级指令,用于引导模型行为。

Default ValueYou are a concise and precise assistant.
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Implementation Guide

Developer documentation

Standard (Async)

POST /api/v1/claude-fable-5-1 — returns request_id, poll for the result via /api/v1/predictions/{id}/result.

curl -X POST https://api.muapi.ai/api/v1/claude-fable-5-1 \
  -H "x-api-key: YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "prompt": "Summarize the key risks in this quarterly report and list follow-up questions.",
    "image_url": "https://example.com/report-page-1.png",
    "system_prompt": "You are a meticulous financial analyst."
  }'

Streaming (SSE)

POST /api/v1/claude-fable-5-1/stream — returns a live Server-Sent Events stream (Content-Type: text/event-stream). Each chunk has the format data: {"choices":[{"delta":{"content":"text"}}]}, ending with data: [DONE].

See Streaming Documentation for full code examples.

Common Questions

Frequently asked

What is Claude Fable 5.1?

Claude Fable 5.1 is Anthropic's newest flagship language model, built for long-horizon agentic coding, multistep research, and document, spreadsheet, and slide analysis, with a 1M-token context window and always-on adaptive extended thinking.

How is pricing calculated?

Pricing is token-based: $10.00 per million input tokens and $50.00 per million output tokens. The minimum charge per call is $0.0008. Actual cost is deducted after each call based on token counts returned by the model.

What is the difference between /claude-fable-5-1 and /claude-fable-5-1/stream?

/claude-fable-5-1 is async — you receive a request_id and poll for the result. /claude-fable-5-1/stream returns a live SSE stream. Use streaming for chat UIs; use the async endpoint for workflows and automation.

Does Claude Fable 5.1 support images?

Yes. Pass an image_url in the request body to include an image — such as a chart, table, PDF page, or screenshot — as part of the user message for multimodal analysis.

How is Claude Fable 5.1 different from Claude Fable 5?

Claude Fable 5.1 adds a larger 1M-token context window, always-on adaptive extended thinking (steerable via effort), and stronger long-horizon agentic and research performance compared to [Claude Fable 5](/playground/claude-fable-5).

Can I control how much the model 'thinks' before responding?

Extended thinking is always enabled and cannot be turned off, but its depth is adaptive to the task — harder, multistep requests automatically get more reasoning effort.