Claude Fable 5.1

Claude Fable 5.1

Anthropic
5.0 out of 5 stars
Claude Fable 5.2

Claude Fable 5.2

Anthropic
5.0 out of 5 stars
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About

Claude Fable 5.1 is Anthropic’s advanced AI model for coding, knowledge work, research, and long-running agentic tasks. It is designed to improve on Claude Fable 5 with stronger performance across software engineering, scientific research, multidisciplinary reasoning, computer use, business workflows, and complex problem solving. The model can handle extended multi-step work, verify its own results, diagnose difficult software issues, and operate effectively across tool-heavy workflows. Anthropic also reduced cache-read pricing for Fable 5.1, lowering typical usage costs compared with Fable 5 and creating larger savings for highly agentic workloads. Fable 5.1 includes updated safeguards intended to reduce false positives while allowing more legitimate cybersecurity tasks such as vulnerability discovery for defensive purposes. The model is available through Claude products, the Claude API, Amazon Web Services, Google Cloud, and Microsoft Azure.

About

Claude Fable 5.2 is an advanced AI reasoning model developed by Anthropic for complex software engineering, scientific research, technical problem-solving, and autonomous agent workflows. The model provides improvements in coding, mathematical reasoning, visual understanding, and long-running task execution compared with previous Claude Fable models. Its agentic capabilities allow AI systems to analyze large codebases, coordinate multiple subagents, develop software, investigate technical problems, and automate complex business processes. Claude Fable 5.2 generates outputs up to 30% faster than Fable 5.1 and offers an optional fast mode that increases generation speed by up to 2.5 times. The model includes configurable reasoning effort, advanced tool use, and specialized cybersecurity and biology safeguards designed to reduce misuse while supporting general technical work.

Platforms Supported

Windows Not Supported
Mac Not Supported
Linux Not Supported
Cloud Supported
On-Premises Not Supported
iPhone Not Supported
iPad Not Supported
Android Not Supported
Chromebook Not Supported

Platforms Supported

Windows Not Supported
Mac Not Supported
Linux Not Supported
Cloud Supported
On-Premises Not Supported
iPhone Not Supported
iPad Not Supported
Android Not Supported
Chromebook Not Supported

Audience

Software developers, researchers, enterprises, analysts, knowledge workers, and AI application teams that need advanced coding, reasoning, research, and long-running agentic capabilities

Audience

Software engineers, AI developers, machine learning researchers, autonomous agent developers, scientific researchers, mathematicians, data scientists, robotics engineers, hardware designers, DevOps professionals, enterprise technology teams, and organizations seeking frontier AI reasoning, autonomous software engineering, complex research automation, advanced coding, technical analysis, and multi-agent workflow orchestration

Support

Phone Support Not Supported
24/7 Live Support Not Supported
Online Supported

Support

Phone Support Not Supported
24/7 Live Support Not Supported
Online Supported

API

Offers API Supported

API

Offers API Supported

Screenshots and Videos

Screenshots and Videos

Pricing

$10 per 1M tokens (input)
$10 per million input tokens and $50 per million output tokens
Free Version Not Supported
Free Trial Not Supported

Pricing

$8 per 1M tokens (input)
$8 per million input tokens and $40 per million output tokens
Free Version Not Supported
Free Trial Not Supported

Reviews/Ratings

Overall 5.0 / 5
ease 5.0 / 5
features 5.0 / 5

Reviews/Ratings

Overall 5.0 / 5
ease 5.0 / 5
features 5.0 / 5

Pros & Cons from Real Users

Pros

  • This feels like the model you reach for when the work is genuinely difficult. Not every task needs Fable, but for complex coding, long-horizon agents, deep research, and big messy knowledge-work projects, Fable 5.1 looks built for the hard stuff. The 1M-token context window is a huge advantage. For developers and AI power users, that means you can work across large repos, long docs, research sets, transcripts, spreadsheets, and project history without constantly chopping everything into pieces. I also like that Anthropic specifically calls out document, spreadsheet, and slide work. That makes it feel useful beyond coding alone — more like a high-end model for serious professional workflows.

Cons

  • The downside is price and complexity. Anthropic says most workloads should start with Claude Opus 5, and Fable 5.1 is better reserved for demanding reasoning or cases where Opus 5 still falls short.

Pros & Cons from Real Users

Pros

  • Fable 5.2 feels like the model I reach for when I have something genuinely difficult and do not want to babysit it the whole way through. The biggest upgrade for me is how well it handles ambiguous, long-running work. I can give it a messy engineering task or a loose idea and it does a much better job figuring out the path, delegating pieces, correcting itself, and actually getting to the finish line.

Cons

  • My only complaint is that this is still a model I would save for the hard stuff. Anthropic itself recommends starting with Opus 5.5 for normal coding and knowledge work, then stepping up to Fable when the task really justifies it.

Training

Documentation Supported
Webinars Not Supported
Live Online Not Supported
In Person Not Supported

Training

Documentation Supported
Webinars Not Supported
Live Online Not Supported
In Person Not Supported

Company Information

Anthropic
Founded: 2021
United States
claude.ai

Company Information

Anthropic
Founded: 2021
United States
claude.ai

Alternatives

Alternatives

GPT-6.1 Terra

GPT-6.1 Terra

OpenAI
5.0 out of 5 stars
GPT-6.1 Terra

GPT-6.1 Terra

OpenAI
5.0 out of 5 stars
GPT-6.1 Sol

GPT-6.1 Sol

OpenAI
5.0 out of 5 stars
GPT-6.1 Sol

GPT-6.1 Sol

OpenAI
5.0 out of 5 stars
Claude Fable 5.1

Claude Fable 5.1

Anthropic
5.0 out of 5 stars
Claude Fable 5

Claude Fable 5

Anthropic
5.0 out of 5 stars

Categories

AI Coding Models Supported
AI Models Supported
AI Vision Models Supported
Foundation Models Supported
Multimodal Models Supported

Categories

AI Coding Models Supported
AI Models Supported
AI Vision Models Supported
Foundation Models Supported
Multimodal Models Supported

Integrations

Buda Supported
C++ Supported
CSS Supported
Charlie Supported
Claude Science Supported
Clawd.run Supported
ClickUp Brain Supported
Doraverse Supported
Emergent Supported
GitAuto Supported
HTML Supported
OfoxAI Supported
PrivatClaw Supported
React Supported
Scala Supported
Scalestack Supported
Trinity-Large-Thinking Supported
Vellum Supported
Verdent Supported
Visual Studio Code Supported

Integrations

Buda Supported
C++ Supported
CSS Supported
Charlie Supported
Claude Science Supported
Clawd.run Supported
ClickUp Brain Supported
Doraverse Supported
Emergent Supported
GitAuto Supported
HTML Supported
OfoxAI Supported
PrivatClaw Supported
React Supported
Scala Supported
Scalestack Supported
Trinity-Large-Thinking Supported
Vellum Supported
Verdent Supported
Visual Studio Code Supported
Claim Claude Fable 5.1 and update features and information
Claim Claude Fable 5.1 and update features and information
Claim Claude Fable 5.2 and update features and information
Claim Claude Fable 5.2 and update features and information