Claude Fable 5
Claude Fable 5 is Anthropic's flagship large language model that ranks at the top of AI benchmarks for software engineering and knowledge work tasks. Released alongside Claude Mythos 5, Fable 5 implements safety restrictions that degrade performance on sensitive domains like cybersecurity and biology, and experienced temporary regulatory scrutiny that led to a brief takedown. Anthropic subsequently released Claude Opus 5 at half Fable 5's price, claiming comparable performance on most tasks while positioning it as a more cost-effective alternative.
Updated 3 August 2026
Specifications
No specifications recorded yet.
Latest developments
Open letters about AI development
Simon Willison · 1 day ago ·
18
Opus 5 vs. Fable 5: What does half the price buy?
The New Stack · 4 days ago ·
36
GPT-5.6 kernel of truth: Sol can cut its own costs, says OpenAI
The New Stack · 4 days ago ·
25
Claude Opus 5 Is Highly Capable, But Is No Mythos
Zvi (Don't Worry About the Vase) · 5 days ago ·
9
Introducing Claude Opus 5
Simon Willison · 1 week ago ·
47
Meet the New Claude Opus 5: Frontier-Class Agentic Coding and Computer Use at Unchanged Opus Pricing
MarkTechPost · 1 week ago ·
29
Introducing Claude Opus 5 on AWS: Anthropic’s most capable Opus model
AWS Machine Learning · 1 week ago ·
34
Anthropic releases Opus 5 with ‘close’ to Fable 5’s capabilities
The Verge · 1 week ago ·
33
August 2026
July 2026
OpenAI releases GPT-5.6 model family with efficiency improvements and significant price reductions Model release
Anthropic releases Claude Opus 5 at half the price of Fable 5 with comparable performance Model release
Anthropic releases Claude Opus 5, matching Fable 5 capabilities at half the price Model release
Moonshot AI releases Kimi K3, a 2.8 trillion parameter open-weight model achieving frontier-class performance Open source release
Moonshot AI releases Kimi K3 open model with 2.8 trillion parameters and 1-million-token context window Open source release
Moonshot AI releases Kimi K3, a 2.8 trillion parameter open-weight model with API pricing and delayed weights availability Model release
Moonshot AI releases Kimi K3, a 2.8 trillion-parameter open-weight model competing with frontier American systems Model release
Anthropic restores Claude Fable 5 after US government suspension over cybersecurity concerns Incident
Claude Sonnet 5 Release and Tokenizer Efficiency Comparison with Competitors Model release
Anthropic extends Claude Fable 5 free access through July 19 for paid subscribers Feature update
OpenAI releases GPT-5.6 model family with three tiers (Luna, Terra, Sol) and new multi-agent capabilities Model release
OpenAI releases GPT-5.6 in multiple variants alongside frontier AI model releases from competitors Model release
Claude Fable 5 Achieves 16.1% Automation Rate on Remote Labor Benchmark Benchmark result
Anthropic redeployed Fable 5 AI model with enhanced safety restrictions following government export controls Feature update
- Opus 5 vs. Fable 5: What does half the price buy?
- GPT-5.6 kernel of truth: Sol can cut its own costs, says OpenAI
- Claude Opus 5 Is Highly Capable, But Is No Mythos
- Introducing Claude Opus 5
- Meet the New Claude Opus 5: Frontier-Class Agentic Coding and Computer Use at Unchanged Opus Pricing
- Introducing Claude Opus 5 on AWS: Anthropic’s most capable Opus model
- Anthropic releases Opus 5 with ‘close’ to Fable 5’s capabilities
- Kimi K3 vs Claude Fable 5 on DeepSWE: Cost and Coding
- Mythos Begets Fable, Cursor's Composer 2.5, Agents Building Agents
- Testing Mythos and Fable, Moving Beyond SWE-bench, Nvidia's Open Contender
- "Drawing" the Mona Lisa with GPT-5.6, Claude, Gemini, and Grok
- LWiAI Podcast #248 - Opus 4.8, MAI, Anthropic IPO, Minimax-M3
- Claude Fable 5 vs. Kimi K3: Same results, one-third the cost, 4x slower
- Anthropic employees worked “literally around the clock” to keep Fable 5 from disappearing
- Alibaba previews 2.4 trillion parameter Qwen3.8-Max model for open release
- Someone Fine-Tuned OpenBMB’s MiniCPM5-1B on Claude Fable 5 Traces to Ship a 657MB Local Thinking Model
- Claude make Fable 5 permanent
- Kimi K3, and what we can still learn from the pelican benchmark
- Restoration of Claude Fable 5, Gemini's Video Dev Engine, DeepSeek Speeds Up Speculative Decoding
- More details on Fable 5’s cyber safeguards and our jailbreak framework
- Redeploying Claude Fable 5
- The Same TypeScript Costs 73% More Tokens on Claude Than GPT
- Claude Fable 5 remains free for paid subscribers through July 19
- Anthropic extends Fable 5 again — and won’t talk about what developers found inside Cursor
- Fable gets another bump
- [AINews] OpenAI launches GPT 5.6 Sol/Terra/Luna, Codex becomes ChatGPT superapp
- The new GPT-5.6 family: Luna, Terra, Sol
- GPT-5.6 Sol Live Testing
- AI #176 Part 1: Doing It Live
- The Sequence Radar #889: Fable 5's Comeback, ZCode's Debut, Claude Science, and the $3.5B Deployment Land Grab
- Claude Fable 5 Scores 16.1% on Remote Labor Index
- AI #175: The Fable Continues
June 2026
Anthropic discontinues Fable 5 model following US government suspension over jailbreak vulnerability Incident
Anthropic releases Claude Fable 5 model with improved benchmarks and new safety restrictions Model release
Relationships
Products & technology
- Anthropic develops this model · 27 sources
- Derived from Claude Mythos 5 · 1 source
- MiniCPM5-1B derived from this model · 1 source
- Microsoft deploys this model · 1 source
- AWS deploys this model · 1 source
- Anthropic deploys this model · 1 source
Regulation
- US Government regulated by this model · 2 sources