Microsoft Brings Anthropic’s Claude Fable 5 to Foundry, Says It’s Coming to GitHub Copilot
Microsoft is bringing Anthropic’s Claude Fable 5 to Microsoft Foundry and said the model is also coming to GitHub Copilot, extending the reach of Anthropic’s first generally available Mythos-class model across Microsoft’s developer tools. Microsoft said the rollout is aimed at long-running, multi-step agent workflows such as code refactoring and research automation.
The customer rollout comes days after The Verge reported that Microsoft had restricted employees from using Fable 5 in GitHub Copilot while its legal teams reviewed Anthropic’s new 30-day data-retention requirements for Mythos-class models. Anthropic launched Fable 5 on June 9 as a safeguarded public version of Mythos 5, with some cyber, biology, chemistry and distillation-related requests rerouted to Claude Opus 4.8.
From the sources (25 posts)
@scaling01RT @claudeai: Introducing Claude Fable 5: a Mythos-class model that we’ve made safe for general use. Its capabilities exceed those of any…
@razrazcleRT @felixrieseberg: Today, we're introducing Claude Fable 5 and Mythos 5, two configurations of our next major language model. I'd normall…
@scaling01Fable 5 has the same underlying weights as Mythos 5 only with additional safeguards
@zephyr_z9"moving from giving AI tasks to giving it responsibilities."
@gavinsbakerEvidently prices will go up in about two weeks. Also I preferred Mythos to Fable. Fable makes me think of fabulist, which is not the best association. Excited to try it!
@hosseebHoly shit. Mythos just dropped (commercially restricted release called Fable), and these benchmarks are making every other lab look like amateurs. Really feels like it's Anthropic's world and we're all just living in it. Can't wait to see
@stocksavvyshayAnthropic announced Claude Fable 5 which is its new Mythos-class model for enterprise and paid users. Claude Fable 5 is also now available in $MSFT Foundry.
@hangsiinWhen Fable 5 is used for frontier LLM development, it does not notify the user and instead limits the model’s capabilities through methods such as prompt modification, steering vectors, and PEFT. Anthropic estimated that this would affect
@dair_aiRT @omarsar0: NEW: Anthropic introduces Claude Fable 5, a Mythos-class model for general use. Beginning of a new class of frontier models.
@jayelmnopRT @claudeai: Introducing Claude Fable 5: a Mythos-class model that we’ve made safe for general use. Its capabilities exceed those of any…
@omarsar0NEW: Anthropic introduces Claude Fable 5, a Mythos-class model for general use. Beginning of a new class of frontier models.
@cryptorover💥BREAKING: Anthropic officially releases its most powerful AI model "Claude Fable" based on Mythos.
@yuchenj_uwClaude Fable 5 / Mythos 5 wins everywhere. I thought Fable 5 was just a nerfed Mythos Preview, but it’s literally better. SWE-Bench Pro: Fable 5: 80.3%, GPT-5.5: 58.6%. And the price is only 2x Opus 4.8: $10/input MTok, $50/output MTok.
@theinsiderpaperBREAKING: Anthropic opens most powerful AI model to public Dubbed Fable 5, the model is the first from the Mythos class — Anthropic’s most advanced lineup of AI technology, unveiled in April but restricted over cybersecurity concerns — to
@alexalbert__RT @claudeai: Releasing a model this capable comes with risks. Without safeguards, Fable 5’s capabilities in areas like cybersecurity could…
@kimmonismusClaude 5 Fable live, even in germany. Insane evals. Tessting time
@andrewcurran_Anyone who had Preview access can now upgrade to the more powerful Mythos 5.
@mlpoweredRT @claudeai: Introducing Claude Fable 5: a Mythos-class model that we’ve made safe for general use. Its capabilities exceed those of any…
@claudedevsIn the API, switch the model ID parameter to "claude-fable-5" in both the Messages API and Claude Managed Agents. For some accounts, an admin may need to enable access first. The /claude-api skill in Claude Code can help you build with Fab
@claudedevsClaude Fable 5 is here. New model generation, new way of working. Here's how to get started in Claude Code and on the Claude Platform: 🧵
@scaling01Fable 5 pricing confirmed at $10/$50 The model will be available in the Pro, Max, Team and seat-based Enterprise plans at no additional cost until June 22nd Afterwards it will require usage credits
@mweinbachClaude Fable 5 (Mythos 5 with safeguards in place, same weights) It's available today, but only available as part of the Claude sub until June 22nd then it will cost extra at API rates. After that, it MAY come to subscriptions if capacity
@cursor_aiClaude Fable 5 is now available in Cursor. It sets a new state of the art on CursorBench at 72.9%, 8 points above the previous best.
@andrewcurran_'We’re making a change to the way we handle business customer data for Fable 5, Mythos 5, and future models with similar or higher capability levels. We will require 30-day retention for all traffic on Mythos-class models, on both first- an
@alexeheathAs Sources reported, Anthropic has released a public version of Mythos