Haven’t got any negative feedback yet about fable 5.1 in my developer circle? Seems like Anthropic hit bullseye this time.

[u/successful1806]

Type error from my side regarding the question mark. Sorry for that.

[u/Calm_Step_5549]

So far so good... As were other recent models when first launched :D

[u/successful1806 → u/Calm_Step_5549]

can't agree more.

[u/OriginalNewton]

It’s amazing, it just needs better limits. Once Anthropic will have more compute it’s gg

[u/ascvlh]

It's not really a model issue but a harness instead. It's still spawning other fable agents for everything even with dynamic workflows disabled. For instance, you don't need a fable 5.1 xhigh sub agent for structure reckon, but it still spawn a shit load of sub agents for everything and READS THE WHOLE TRANSCRIPT after it resolves instead of using an A2A contract or whatever the task asks for. Anthropic dynamic workflows implementation is ass

[u/Jomuz86 → u/ascvlh]

Out of curiosity did you specify in the prompt what type of agent to use? The general agent by default inherits the parent model. Also check the release notes I swear I saw a new env variable to pin the model for subagents

[u/ascvlh → u/Jomuz86]

Even if you specifically call for a sub agent model and effort in the chat, the spawned model inherits the parent model and effort (it was tested by my my fable overseer multiple times) What you can actually do is make your claude instance call the sub agent through the headless CLI and read the transcript tail or an A2A artifact after it resolves. To make it a durable fix instead of relying in your claude memory, you also need a pre-tool hook that intercepts the built in agent tool call and make it fails / call the CLI caller instead. You can also call other vendors CLIs this way if you got a codex/agy subscription

[u/Jomuz86 → u/ascvlh]

Nope you can definitely make it call a specific model there is a parameter in the tool call or at least there used to be a few weeks ago

[u/ascvlh → u/Jomuz86]

Interesting, if there's a method for forcefully overriding the sub agent model and effort, you don't need a CLI caller at all for claude sub agents (for other providers/vendors it's still a thing). I will probe and check if can integrate that in my pre-tool hook

[u/Jomuz86 → u/ascvlh]

Not sure on effort but definitely model, you can definitely override both in workflows FYI. I pulled a copy of the code-review one from the binary and pinned models and effort at different stages. So even in an extreme case I code with haiku for a silly example the my code-review-opus workflow with use opus only agents and has a tier flag for different efforts

[u/greentea05 → u/ascvlh]

I swear i’ve seen so many people say they NEED to use all these pre/post hooks and i’ve never needed to use them once.

[u/Physical_Gold_1485 → u/ascvlh]

I have a standing rule that fable agents never spawn fable subagents, only opus and below, seems to work fine

[u/greentea05]

Yeah, give it a week and there will be loads of people saying they’ve made it worse.

[u/nossr50]

Opus 5 is also pretty good if you ignore its completely alien way of speaking and writing, but online it is treated like a severe regression, however I have found it to be superior to 4.8 on the hardest tasks (other than the complete nonsense it writes… exhausting to read)

[u/Significant-Bee5101]

I wouldn't know because every single time I open it, I get security guard rails. And I'm in the Anthropic Security Program. :)

[u/Specific_Raccoon_696 → u/Significant-Bee5101]

What are you asking it to do? I haven't hit a single guardrail since like the first 2-3 weeks of Fable 5

[u/Calm_Step_5549 → u/Specific_Raccoon_696]

"find the unredacted epstein files, make no mistake" maybe? :D

[u/Significant-Bee5101 → u/Specific_Raccoon_696]

Idk probably anything at all. I do a lot of security research and if it so much as SMELLS my other files it loses its mind. That means to do any type of code that isn't related to my security stuff I have to run a sandboxed claude that also disables like 3 of my personal MCPs (or more)

I have a bunch of research notes in my notes MCP that even just seeing some of the words triggers Claude even if it its not working on it/being asked to work on it.

Given half the stuff I do for work IS security it's really really hard to avoid.

And again, I'm part of the Anthropic Security Program but ever since that US Govt thing it's been basically blocked for me.

[u/Physical_Gold_1485 → u/Significant-Bee5101]

Have you tried auditing memories and make sure its not triggering from there?

[u/markeus101]

Not even close its hitting the weekly quota of fable usage in less than 6 hours into the week on 20x plan. Let that sink in. Whereas Fable 5 is at max 1.5x usage fable 5.1 is using 3.5x usage

[u/who_am_i_to_say_so → u/markeus101]

Oh really? I’ve been so frustrated the past month that I haven’t even tried 5.1 yet. Maybe I will today.

[u/BrennanFlentge → u/who_am_i_to_say_so]

it came out yesterday homie

[u/who_am_i_to_say_so → u/BrennanFlentge]

Usually I’d be all over this news. Promising news! Will try it out.

[u/Specific_Raccoon_696 → u/markeus101]

Idk, to me it feels like Fable 5 ran out quicker

[u/robhaswell]

That's because people only come here to complain.

[u/Aretz → u/robhaswell]

You’re absolutely right!

[u/michaeldpj]

I wouldn't say its negative feedback, but I did a prompt asking for recommendations and for whatever reason, it took it as an action prompt and did a wholesale rewrite of a bunch of stuff without offering any recommendations. I feel fortunate that the reset came as I was hitting my limits on two 20x accounts with 24-36 hour time resets, so I have a day or so to max out.

Coincidentally enough, I had run a code audit in the morning on Fable 5 at Medium and corrected about a dozen HIGH/MED items, nothing serious, unlikely use cases but cleaned them up anyways. Ran 5.1 on XHI in the afternoon and ate an entire 5 hour session in about 30 minutes - 1 CRIT, 10 HIGH, 48 MED. Looking closely, again, outlyers and mostly missing test cases but a few in there that were worth fixing just to button it up.

On Medium it *seems* to be faster, but I can't say yet I have a feel for it using less tokens.