Claude Fable 5.1

Specifications

No specifications recorded yet.

Latest developments

Muse Wonder vs. Claude Fable 5.1: Meta’s new model came closer than I expected The New Stack · 3 days ago · 13

llm-gemini 0.35 Simon Willison’s Weblog · 5 days ago · 41

Meta’s Muse Wonder Matches Claude Fable for Less Trending Topics · 6 days ago · 34 Import AI 475: Swarm scaling; Google DeepMind watermarks biology; and the AI science economy Import AI · 2 weeks ago · 5 GPT-6 Astra vs GPT-6.1 Sol vs Gemini 4 Argon vs Claude Fable 5.1: Which Frontier Model Fits Which Job MarkTechPost · 2 weeks ago · 36

Google Finally Brings Gemini 4 Into the Fight Against Anthropic and OpenAI Trending Topics · 2 weeks ago · 12

Claude Opus 5.5 vs. Fable 5.1: One overthinks, the other cuts corners The New Stack · 2 weeks ago · 33

[AINews] Claude Opus 5.5, the new default model for AINews — and everybody cuts prices 40-50% Latent Space · 3 weeks ago · 43

2026

◆ Google released and began rolling out its Gemini 4 Argon frontier AI model across its API and Google products with tiered access and introductory token pricing Model release

◆ Meta released the Muse Wonder model family and the Muse Spark Open open-weight model for AI agent and coding workloads Model release

◆ OpenAI launched GPT-6.1 Sol and cancelled its earlier GPT-6.1 Astra model after internal testing Product launch

◆ Google DeepMind announces Gemini 4 Argon, a frontier AI model with up to 1 million output tokens and phased, limited access for trusted cybersecurity users Model release

◆ Anthropic launches Claude Sonnet 5.5, a faster and lower-cost work model in the Claude 5.5 family Model release

◆ Anthropic releases Claude Opus 5.5, reducing API token prices and adding routing behavior for some requests Model release

◆ Evaluators stress-tested OpenAI’s GPT-6 Astra on one-shot build tasks and a physical driving benchmark Benchmark result

◆ New coding and agent benchmarks using private, tool-enabled tasks show large drops in pass rates and limited consistency across repeated runs Benchmark result

◆ OpenAI released GPT-6 Astra, a new model positioned as a major upgrade over prior generations, with specified per-token input and output pricing Model release

◆ Agents on Rails benchmark leaderboard updated with rerun results for Anthropic Claude Fable 5.1 and Z.ai GLM 5.3 Flash Benchmark result

◆ OpenAI launches GPT-6 Astra and begins a staged rollout to selected users and partners, followed by broader availability Model release

◆ OpenAI released GPT-6 Astra, its flagship AI model, along with evaluation results, a system card, and related updates to how the model is benchmarked and priced Model release

◆ Simon Willison posted monthly LLM digest and briefing updates, including an option to subscribe via sponsorship Other

◆ Anthropic released the Claude Fable 5.1 and Claude Mythos 5.1 AI models with updated pricing and restricted availability for vetted organizations. Model release

◆ Anthropic launched Claude Fable 5.1, a developer-tools offering based on its Claude foundation models for coding and knowledge work Model release

◆ Anthropic released Claude Fable 5.1 and Claude Mythos 5.1, including changes to agent API behavior and watermark-based text detection. Model release

◆ Anthropic released updated Claude models Fable 5.1 and Mythos 5.1 with lower cache-read pricing and modified access and safeguards Model release

◆ Anthropic launches Claude Fable 5.1 and Claude Mythos 5.1, including AWS Bedrock availability and agentic-work pricing changes. Product launch

◆ Anthropic adjusted Claude Code usage limits effective September 14 and reported a reduction in Claude cache read costs Pricing change

• 16 Oct Muse Wonder vs. Claude Fable 5.1: Meta’s new model came closer than I expected
• 13 Oct llm-gemini 0.35
• 13 Oct Meta’s Muse Wonder Matches Claude Fable for Less
• 5 Oct Import AI 475: Swarm scaling; Google DeepMind watermarks biology; and the AI science economy
• 4 Oct GPT-6 Astra vs GPT-6.1 Sol vs Gemini 4 Argon vs Claude Fable 5.1: Which Frontier Model Fits Which Job
• 30 Sep Google Finally Brings Gemini 4 Into the Fight Against Anthropic and OpenAI
• 29 Sep Claude Opus 5.5 vs. Fable 5.1: One overthinks, the other cuts corners
• 23 Sep [AINews] Claude Opus 5.5, the new default model for AINews — and everybody cuts prices 40-50%
• 22 Sep Anthropic Releases Claude Opus 5.5: Fable 5.1-Level Performance at 40% Lower Running Cost Than Opus 5
• 21 Sep GPT-6 Astra and Claude Fable Rarely Refuse Dangerous Robot Commands, Test Finds
• 14 Sep AI’s best coding agent fails 60% of the time — and the data backs it up
• 14 Sep How GPT-6 Became No. 1: Artificial Analysis CEO Explains The Much-Debated Index Updates
• 11 Sep Datasette 1.0a39 and 0.65.4 security releases
• 10 Sep Fable 5.1 vs. Fable 5: Results on a real-world budget, not the spec sheet
• 10 Sep Agents on Rails: Fable 5.1 & GLM 5.3 Flash
• 9 Sep LWiAI Podcast #256 - Fable 5.1, Astra Tease, Gemini 3.8 Flash
• 8 Sep GPT-6 Astra Now on Par With Claude Fable 5.1 in Updated Artificial Analysis Index
• 7 Sep Last Week in AI #343 - GPT-6, OpenAI’s agents chatted on a wiki, Fable 5.1
• 6 Sep 🔮 Astra outruns visibility EV#600
• 5 Sep Claude Mythos 5.1 and Fable 5.1: Capabilities
• 5 Sep Claude Fable 5.1 vs. Fable 5: On real work, I couldn’t tell them apart.
• 5 Sep GPT-6 Still Behind Fable 5.1 As Artificial Analysis Overhauls Intelligence Index
• 4 Sep Claude Fable 5.1 and Mythos 5.1: The System Card
• 4 Sep Deep Learning Weekly: Issue 471
• 3 Sep GPT‑6 Astra
• 3 Sep It cost $33 to build a virtual Union Square. Here’s what the agents got wrong.
• 2 Sep llm-anthropic 0.28
• 2 Sep 😺 Claude Fable 5.1 can do the work. The hard part is managing it.
• 2 Sep Fortune Tech: Anthropic Fable and Mythos 5.1, OpenAI Astra limits, AI token tax
• 2 Sep The Sequence Learning Loop - Issue 925: Learn About Fable and Mythos 5.1, GLM-5.3-Flash, and Qwen 3.8
• 2 Sep 😺Anthropic launched Fable 5.1: and now, the agents cost less
• 2 Sep [AINews] Claude Fable/Mythos 5.1: new SOTA model, 75% cache price cut but 70% more output tokens
• 2 Sep Fable 5.1: The New Best AI Model Is Once Again More Expensive
• 1 Sep Claude Fable 5.1 made me a really nice animated pelican
• 1 Sep Claude Fable 5.1 watermark: It has a blind spot developers can’t ignore
• 1 Sep Anthropic launches Claude Fable 5.1 after inking $35B cloud deal with Lambda
• 1 Sep Anthropic Releases Claude Fable 5.1 and Claude Mythos 5.1: 52.6% on Terminal-Bench-Science and 75% Cheaper Cache Reads
• 1 Sep Anthropic’s Fable 5.1 is a bit cheaper, a bit smarter, and refuses a lot less
• 1 Sep Introducing Claude Fable 5.1 on AWS
• 1 Sep Anthropic launches Claude Fable 5.1 and says it’s up to 45 percent cheaper for agentic work
• 1 Sep Claude Fable 5.1

Relationships

Products & technology

• Anthropic develops this model · 20 sources
• Integrated with Enterprise Frontier Safeguards · 2 sources
• Anthropic deploys this model · 2 sources
• Artificial Analysis integrated with this model · 2 sources
• Deploys Agents on Rails · 1 source
• Deploys Terminal-Bench-Science 0.1 · 1 source
• Deploys pelican · 1 source
• Integrated with Terminal-Bench-Science 0.1 · 1 source
• Deploys Claude API · 1 source
• Deploys AWS · 1 source

Investment & ownership

• Anthropic owns this model · 2 sources

Competition

• Competes with Opus 5 · 1 source