Claude Fable 5.2

Claude Fable 5.2

Anthropic
5.0 out of 5 stars
Muse Spark Open

Muse Spark Open

Meta
5.0 out of 5 stars
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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.

About

Muse Spark Open is an open-weight, natively multimodal language model for developers and organizations building AI applications, coding systems, and agentic workflows. The released model has 816 billion total parameters, 42 billion active parameters, and a 1-million-token context window. Teams can download the model weights, run inference through supported engines such as vLLM, SGLang, TensorRT-LLM, Hugging Face Transformers, Apple MLX, llama.cpp, or Unsloth, and customize the model using PyTorch. It supports long-context reasoning, software engineering, coding, tool use, and multimodal inputs. Deployment options include cloud inference through listed API providers or self-hosting on compatible GPU systems; Meta documents a desktop setup using two Apple M5 Ultra Mac Studio computers. The model is released under the Muse Model License with limited commercial terms.

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

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

Audience

AI developers, machine learning engineers, software engineers, AI researchers, enterprise development teams, and organizations seeking customizable open-weight multimodal models for local inference, autonomous agents, complex coding, and long-context AI applications

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 Not Supported

API

Offers API Supported

API

Offers API Not Supported

Screenshots and Videos

Screenshots and Videos

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

Pricing

$0
Model weights are available at no charge under the Muse Model License, which has limited commercial-use terms. Hosted inference providers set their own usage prices.
Free Version 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

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.

Pros & Cons from Real Users

Pros

  • Meta finally opened up a genuinely frontier-level Muse model. The 1M-token context window and 42B active parameters make it strong enough for large repos, long agent sessions, multimodal work, and complex coding without feeling like a stripped-down open model. The local deployment story is also a huge deal. Being able to run something this capable on two M5 Ultra Mac Studios is impressive, especially for teams that want more control over data, infrastructure, and customization. I also like how much of the stack is open around it. Muse Spark Open works with MLX, vLLM, SGLang, TensorRT-LLM, Transformers, llama.cpp, and Unsloth, and Meta is making the weights available through Hugging Face, SageMaker, Google Cloud Model Garden, and Microsoft Foundry.

Cons

  • Even though it is technically desktop-capable, needing two M5 Ultra Mac Studios for the full local experience is still a serious setup, so most developers will probably use hosted inference instead.

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

Meta
Founded: 2004
United States
research.meta.ai/blog/muse-spark-open

Alternatives

Alternatives

Claude Fable 5.2

Claude Fable 5.2

Anthropic
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 Terra

GPT-6.1 Terra

OpenAI
5.0 out of 5 stars
Claude Fable 5.1

Claude Fable 5.1

Anthropic
5.0 out of 5 stars
Recursive Flint

Recursive Flint

Recursive
Claude Fable 5

Claude Fable 5

Anthropic
5.0 out of 5 stars
Muse Glimmer

Muse Glimmer

Meta
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

Integrations

Aider Supported
Amazon Bedrock Supported
App0 Supported
BLACKBOX AI Supported
Brokk Supported
CSS Supported
Claude Supported
Claude Code Supported
Claude Design Supported
Claude Pro Supported
Cursor Supported
GitHub Supported
Hermes Agent Supported
Lovable Supported
Muse Supported
Revise Supported
Scalestack Supported
Together AI Not Supported
Visual Basic Supported
Zo Computer Supported

Integrations

Aider Not Supported
Amazon Bedrock Not Supported
App0 Not Supported
BLACKBOX AI Not Supported
Brokk Not Supported
CSS Not Supported
Claude Not Supported
Claude Code Not Supported
Claude Design Not Supported
Claude Pro Not Supported
Cursor Not Supported
GitHub Not Supported
Hermes Agent Not Supported
Lovable Not Supported
Muse Not Supported
Revise Not Supported
Scalestack Not Supported
Together AI Supported
Visual Basic Not Supported
Zo Computer Not Supported
Claim Claude Fable 5.2 and update features and information
Claim Claude Fable 5.2 and update features and information
Claim Muse Spark Open and update features and information
Claim Muse Spark Open and update features and information