Is it just me, or has Opus suddenly turned dumb as rocks with 0 attention span over the last half day or so? Noticeably worse output across multiple agents on very different projects.
There was an article on HN a month or so about benchmarking Opus 5.5 every day and recording / publishing the results. I recall this being a github repo, but my searches turned this up instead: https://www.bridgebench.ai/nerf-bench/claude-opus-5-5
So it seems like ... it is not getting dumber. I find myself using Fable a lot more, though. Opus 5.5 was never as fun as Fable, but it's pretty good.
Opus 5.5 is definitely good. I use both all day and it's really hard to say which is which from looking at the outputs; I can't read a PR and say "this was Fable" or "this was Opus" like I could pre-5.5.
Fable is better at playing along with my "You are a dog" instruction in CLAUDE.md. It is willing to be fun and playful, whereas Opus just wants to finish the job and go home. Friend vs. coworker, basically. For example, whenever I reward Fable with a dog treat (actually a <cookie emoji>, which I tell it is a chocolate-free chocolate chip cookie) it keeps a log in memories. Opus just says "crunch! tail wagging!" and moves on.
None of this matters but I think it's fun to have some fun :)
I’ll ask the same question as when it came out: if you don’t trust the provider how are you trust them not to look for and cheat on repeat benchmarks like this.
I found your post because I searched "Did Opus 5.5 get worse today?". I experienced the same thing with it not following instructions well and just missing things.
I think something has changed, maybe about two weeks ago, because there’s this fixation from the model where if you ever need to make a correction, it simply becomes disinterested with your instructions.
Agreed. Yet, it munches tokens like there's not tomorrow. I don't get anything done with Claude in the past 2-3 weeks - just eating up its weekly quota within a day.
It is dumb. None of my threads were closed with shipped features. It keeps going into endless review cycles essentially burning all my quota within a couple of days. And I'm not talking about complex a features an OpenAPI-based integration and some enhancement of pytest traces building maps of touched files. Both these are in their second week of token burn!
Honestly depending on what you're doing, consider Gemini + Claud combo. Use Opus/Fable for design/architecture/complex work and have Gemini Flash 3.8 do the code gen and the rest of the simple stuff.
Is it just me, or has Opus suddenly turned dumb as rocks
What I've seen is that if I let Opus 5.5 run for too many turns (not sure how to quantify that) it starts exhibiting signs of human dementia. It will forget it told me to run something and will then accuse me of misconfiguring something that it literally gave me a script to run that configures something. It also forgets the instructions in my project and has to go back and read them and apologizes for forgetting the instructions. Between this increasing context rot and the excessive shock collars applied to defensive security coding it's rare that I can even use Opus 5.5. For the past few weeks I have had to use Opus 4.8 and even that now has a sub-set of the shock collars applied [cyber] which forces me to start a new session. This has led me to researching the Abliterated 70B/120B (uncensored) models and required hardware.
So dumb as rocks? I am not seeing that, but the context rot is getting worse for me personally. I don't know if it makes a difference, I am on the pro 20x plan. Maybe people on enterprise plans do not see this which I assume is most of the people here using Claude.
So it seems like ... it is not getting dumber. I find myself using Fable a lot more, though. Opus 5.5 was never as fun as Fable, but it's pretty good.
Fable is better at playing along with my "You are a dog" instruction in CLAUDE.md. It is willing to be fun and playful, whereas Opus just wants to finish the job and go home. Friend vs. coworker, basically. For example, whenever I reward Fable with a dog treat (actually a <cookie emoji>, which I tell it is a chocolate-free chocolate chip cookie) it keeps a log in memories. Opus just says "crunch! tail wagging!" and moves on.
None of this matters but I think it's fun to have some fun :)
I’ll ask the same question as when it came out: if you don’t trust the provider how are you trust them not to look for and cheat on repeat benchmarks like this.
https://github.com/ninjahawk/livenerf
you, and they, might be getting a/b tested
What I've seen is that if I let Opus 5.5 run for too many turns (not sure how to quantify that) it starts exhibiting signs of human dementia. It will forget it told me to run something and will then accuse me of misconfiguring something that it literally gave me a script to run that configures something. It also forgets the instructions in my project and has to go back and read them and apologizes for forgetting the instructions. Between this increasing context rot and the excessive shock collars applied to defensive security coding it's rare that I can even use Opus 5.5. For the past few weeks I have had to use Opus 4.8 and even that now has a sub-set of the shock collars applied [cyber] which forces me to start a new session. This has led me to researching the Abliterated 70B/120B (uncensored) models and required hardware.
So dumb as rocks? I am not seeing that, but the context rot is getting worse for me personally. I don't know if it makes a difference, I am on the pro 20x plan. Maybe people on enterprise plans do not see this which I assume is most of the people here using Claude.
My best guess was also that in one or two days they will drop a new model that will be so much more better than the nerfed 5.5.