Only three days after the release of Claude Fable 5, Anthropic was forced by the United States Government to make it unavailable, when a jailbreak was brought to its attention, rather than the previous situation of ‘yes obviously experts can jailbreak anything if they care enough’ and ‘yes obviously you can ask Fable to fix your code.’

Three days was enough time for many of us to learn to love Fable, and for us to dearly miss it now that it is gone. The world was briefly smarter, and now it is again stupider. At some point it will get smarter again, which will likely be within two weeks.

This post is written as if Fable 5 is again available for public use, rather than trying to include a lot of qualifying clauses. It remains to be seen how this will play out, and this post does not attempt to cover that question.

My previous release coverage of Fable covered the model card and then model welfare. Coverage of the government takedown of Fable starts here, and continues here and here.

The Official Pitch

The pitch is that Fable 5 is the best model [...]

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Outline:

(01:08) The Official Pitch

(04:06) Technical Details

(04:31) The System Prompt and Jailbreak

(06:45) Benchmarks

(15:22) Other People's Benchmarks

(21:08) The Classifiers Are Not Messing Around

(22:53) The Classifiers Need Work

(28:15) The Classifiers Have Consequences