Claude Fable

Introducing Claude Opus 5.5, the first model in our new Claude 5.5 family. It performs at the level of Claude Fable 5.1 for most tasks, and costs 40% less to run than Opus 5. https://t.co/Q9C2VKQ79f

@claudeai·Sep 22, 2026↗

A few notes on Anthropic's new Claude Fable 5.1 - with Max thinking level I got the best SVG pelican I've had from any Anthropic model (at a hefty cost of $3.30!), which I then had it animate https:/…

@simonw·Sep 2, 2026↗

🚰 SYSTEM PROMPT LEAK 🚰 Here's the Fable 5.1 system prompt!! 🙌 Coming in at a WHOPPING 270,000+ characters, this prompt is definitely on the longer side. There have been a handful of notable edit…

@elder_plinius·Sep 1, 2026↗

We’re introducing Claude Fable 5.1 and Claude Mythos 5.1. They're the world’s most advanced models for coding and knowledge work. https://t.co/8P9PSrWPi3

@claudeai·Sep 1, 2026↗

We're extending Claude Fable 5 access on all paid plans, as well as keeping Claude Code’s weekly rate limits 50% higher, through July 19.

@claudeai·Jul 12, 2026↗

OpenAI just made GPT-5.6 available to everyone, so I wanted to answer the most burning question: Is GPT-5.6 better than Claude Fable 5? I tested both models across 6 real use cases: → Frontend des…

@petergyang·Jul 9, 2026↗

Here's my in-depth guide to getting the most out of Claude Fable 5, so you can build things as insane as my demos below. https://t.co/XemOHH7K8E

@mattshumer_·Jul 4, 2026↗

A Field Guide to Fable: Finding Your Unknowns Working with Claude Fable 5 keeps re-teaching me an old lesson: the map is not the territory. The map, a representation of the work to be done, is my p…

@trq212·Jul 3, 2026↗

A conversation with Boris Cherny and Cat Wu on the path from Claude Code to Claude Tag, and how it spread from engineering to the rest of Anthropic. Claude Fable 5 is now available in Claude Tag. ht…

@claudeai·Jul 2, 2026↗

Claude Fable 5 will be available again globally tomorrow. After a series of productive conversations with the US government, we're redeploying the model with a new set of classifiers to target and b…

@AnthropicAI·Jul 1, 2026↗

Kimi K2.7 Code vs Claude Fable 5: Landing pages that cost 94% less We ran an experiment where we had Kimi K2.7 Code and Claude Fable 5 each produce 12 landing pages for a side‑by‑side comparison. Ov…

@nutlope·Jun 17, 2026↗

After two days with Claude Fable 5 the best way I can describe it is "relentlessly proactive" - here's an example where I dropped in a screenshot of a bug and it span up custom CORS Python servers an…

@simonw·Jun 12, 2026↗

Claude Fable can run autonomously for days. This is the single highest-leverage prompt I use to stay on top of it: "Spin up a persistent HTML page. As you work, append clear, timestamped updates wi…

@mattshumer_·Jun 11, 2026↗

Getting the most out of Claude Fable 5, Anthropic’s powerful new model, you need to maximize your ambition: It’s built for full task delegation—you leave it looping for hours or overnight and come b…

@danshipper·Jun 10, 2026↗

Designing loops with Fable 5 Mythos-class models like Claude Fable 5 have changed the way many of us work at Anthropic. I want to share two tips for getting the most out of this class of models. Se…

@RLanceMartin·Jun 10, 2026↗

Wrote up my initial impressions of Claude Fable 5 - it has a big model smell: slow, expensive and capable of crunching through pretty much everything I threw at it https://t.co/xLybVGiR4c

@simonw·Jun 10, 2026↗

Claude Fable 5 changed how we work on the Claude Code team day to day. We used to verify that Claude did the work right. Now we verify that it's doing the right work. Here’s the 3 biggest changes: …

@ClaudeDevs·Jun 9, 2026↗

I've had access to Fable for a bit. A genuine jump in capability, I could feed it a 15 page design document for a project and it would work for 9+ hours and deliver terrific results. But working wi…

@emollick·Jun 9, 2026↗

Introducing Claude Fable 5: a Mythos-class model that we’ve made safe for general use. Its capabilities exceed those of any model we’ve ever made generally available. https://t.co/2AvmEjHIX8

@claudeai·Jun 9, 2026↗

BREAKING: Anthropic just dropped Claude Fable 5—this is Mythos, made safe for public release. It is the best coding model in the world. We've been testing it internally @every for the last week or …

@danshipper·Jun 9, 2026↗