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Claude Fable 5
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Claude Fable 5

Fable 5 (claude-fable-5) · Family: Claude
Anthropic's Mythos-class model released for general use with safeguards. State of the art across software engineering, knowledge work, vision and scientific research.
✓ Active✓ Public accessLLMMultimodalReasoning modelTool-using model📁 Claude
Context window
1M
tokens
Max output
128,000
tokens
Release date
9 June 2026
🏢AnthropicProducer
Access:APIHostedDeployment:☁ Cloud

Overview

Claude Fable 5 is a Mythos-class model developed by Anthropic and made generally available on 9 June 2026. According to the company its capabilities exceed those of any model Anthropic had previously released for general use, reaching state of the art on nearly all tested benchmarks, including software engineering, knowledge work, vision and scientific research. The model's lead grows with the length and complexity of the task.

Fable 5 shares the same underlying model as Claude Mythos 5, the difference being its safeguards. When safety classifiers detect a request related to cybersecurity, biology and chemistry, or distillation, the response is handled by Claude Opus 4.8 instead. Anthropic reports that more than 95% of sessions involve no fallback. The model is available through the Claude API as claude-fable-5 at 10 USD per million input tokens and 50 USD per million output tokens.

Classification
LLMMultimodalReasoning modelTool-using model
Family: Claude
Access & deployment
APIHosted
Cloud
Weights: Closed
Key parameters
📏 Context: 1M
✓ Tools
📥 Input: text, image, documents

Technical specification

Context window
1M
tokens
Max output tokens
128,000
tokens per response
Features:✓ Tool use
Modalities
⬇ Input
textimagedocuments
⬆ Output
textcode

Capabilities and applications

Native model capabilities
Reasoning
The model's ability to reason logically and solve complex problems.
Category: reasoning
Multi-step reasoning
Carrying out multi-step chains of reasoning across long, complex tasks.
Category: reasoning
Long context
Support for large context windows — tens to hundreds of thousands (or millions) of input tokens. Enables analysis of entire codebases, long documents, and many parallel conversations without losing earlier information. GPT-5.1 supports 400,000 tokens.
Category: language
Coding
Generating, analysing and modifying code in many programming languages. Covers writing functions, debugging, refactoring, code review, and creating tests. Measured by benchmarks such as HumanEval and SWE-bench.
Category: coding
Function Calling
Category: planning
Structured output
Producing data in structured formats such as JSON.
Category: structured_generation
Image understanding
Analysing and interpreting the content of images.
Category: vision
Chart understanding
Reading and interpreting charts, tables and diagrams.
Category: vision
OCR
Recognising text within images and documents.
Category: vision
Multilingual
Competence in many natural languages (from a few to over a hundred): understanding, generation, translation, and code-switching within a single conversation. Frontier models support a wide range of languages with comparable quality.
Category: language
Planning
Forming and executing action plans for complex tasks.
Category: planning

Pricing

Technical architecture

Sources and related pages