🚀 AI agents can now handle even longer, harder coding and science work with less babysitting. Title: Introducing Claude Fable 5.1 and Claude Mythos 5.1 URL: 📊 Overview Anthropic released two new models built on the same underlying model with different safety configurations: Claude Fable 5.1 (general availability) and Claude Mythos 5.1 (restricted, vetted access). 🎯 Problem Solved The release targets three challenges: maintaining reasoning quality during long unattended runs, stronger self-verification in complex workflows, and reducing safety false positives that hurt legitimate users. 🔬 Methodology and Approach Mythos 5.1 is limited to vetted professionals through the Cyber Verification Program and Life Sciences Verification Program, while Fable 5.1 ships broadly as the standard model. New Enterprise Frontier Safeguards add zero data retention, and new anti-distillation protections block illicit capability extraction. 📈 Results Agentic scientific research benchmark scores jumped from 24.7% to 52.6%, and agentic coding scores from 42.0% to 55.8%. The model designed protein binders with 10x the affinity of competition winners and produced a new high-resolution Venus elevation map. Cache read pricing dropped 75%. #ClaudeFable# #AIAgents#

Claude Fable 5.2 from @AnthropicAI is on Snowflake Cortex AI the same day it launched. 🛠️ Point it at a loosely defined engineering project, like moving a production service from Python to Rust, and let it handle the long, multi-agent work. Now in private preview.

Claude Fable 5.2 and Mythos 5.2 share a model. Fable is widely available. Direct Mythos access is reserved for vetted organizations doing cybersecurity or biomedical work.

Claude Fable 5.2 is now available in Perplexity Computer for Pro and Max subscribers, and in Search for Max subscribers. On our WANDR benchmark, it achieved Pareto frontier of performance and efficiency, with a record score of 0.851 at $14.51 per task.

CLAUDE FABLE 5.5 MIGHT BE MUCH CLOSER THAN PPL EXPECT Google just dropped Gemini 4 Argon, and Polymarket is giving it 69% odds of being the best AI model by the end of October I don't think Anthropic will let that narrative sit with the IPO getting closer. A major Claude upgrade would make a lot of sense rn On Oct 13, Claude Fable 5.5 showed up in Azure Models API and disappeared shortly after Polymarket still has Fable 5.2+ by Oct 17 at just 47.5%, while Oct 21 is already at 79.5% With liquidity this thin, I'd rather leave a limit on @tradenomos and wait for my price If that Azure leak was real, I think Oct 17 is where the interesting trade is

Claude fable 5.5 made this entire video. It researched the breakthroughs, wrote the script, built 21 3D scenes, composed the music in code and rendered 3,240 frames. AI went from "strawberry" to claiming a Millennium Prize in 2 years. Here are the next 10:

Claude Opus 5.5 is now available as the Standard effort level in Perplexity Computer. On our WANDR benchmark, it scored 0.610 at $4.13 per task, slightly outperforming Claude Fable 5.1 while costing 67.6% less per task.