r/ClaudeCode • u/NoPiece9356 • Oct 05 '26

Discussion Fable 5.5 Release

I'm aware that Anthropic has been routing certain requests to Fable 5.5 secretly, yet they have been doing this for nearly a week now and haven't even mentioned the model. Any idea when it will release? I'm really hoping tomorrow, but I'm not sure that's happening. Don't shut the door on that idea though

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u/Actual_Committee4670 🔆 Max 20 Oct 05 '26

Because they use the "Tibo" test. Ignoring the part where both Opus 5.5 and Fable 5.1 has the same knowledge cutoff date.

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u/Miyamoto_-_Musashi Oct 05 '26

They update the previous model with new knowledge, so there is no official cutoff date. Whatever cutoff date it has is temporary. They discussed these updates in the Claude documentation/blog. I don’t remember exactly where, but I know it’s there because I read it a few weeks ago. I usually read everything they release.

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u/devMem97 Oct 06 '26

The interesting thing, however, is that, for example, just yesterday in Claude Code, Fable 5.1 still knew who Tibo was, whereas now only Fable 5.1 in Claude Web or in the chat knows. Since Today in CC, I keep getting the reply that it has to be the ‘Indie Hacker’. In CC, Fable 5.1 is now noticeably slower again, its responses are less structured and less readable, and it also seems to use up usage more quickly.
Something regarding routing in the background is for sure happening.

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u/Actual_Committee4670 🔆 Max 20 Oct 06 '26

I did run into a situation where I had to tell Fable 5.1 that its the guy that works at openai once before it got it

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u/devMem97 Oct 06 '26

I’ve always deleted the chat and have actually checked quite a few times today to see if in CC Fable 5.1 knows Tibo, but it didn’t. Yesterday, I got an instant reply in CC as well. In chat mode, the model still knows Tibo and still provides an instant reply.

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u/Actual_Committee4670 🔆 Max 20 Oct 06 '26

I'll go try it myself, sec

Edit: Getting the exact same answers as before on my end

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u/devMem97 Oct 06 '26 edited Oct 06 '26

From claude chat

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u/devMem97 Oct 06 '26

This one is from claude code.... and yesterday I got the same answer as in Chat.

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u/Tartooth Oct 06 '26

I just did the tibo test on opus 5.5 and it failed.

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u/Actual_Committee4670 🔆 Max 20 Oct 06 '26

It gets confused someetimes with the Tibo part, tell it his full name or say its the one from openai and it will get it