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Posted by espeed 21 hours ago

Fable 5 – Median thinking declined in August(twitter.com)
398 points | 282 commentspage 2
dooglius 20 hours ago|
> Instead of finding a nerfed model, after six weeks of reconstructing wire logs, parsing transcripts, analyzing output tokenization, and staring at data, I found a much deeper issue. The model identity had remained the same, but the inference regime being delivered behind that model had not.

Is this something specific that shows up in the wire log, or is this the author's intepretation? The fact that Claude Code versions change over time in the test is suspicious. Anthropic has stated in the past that the underlying model behavior does not change over time, but Claude Code will change from version to version and this is expected. So if it's just Claude Code more aggressively tuning some knob in its requests, that's a pretty different thing than the underlying model changing.

Aurornis 19 hours ago|
They posted a long document explaining it all https://x.com/Lon/status/2101034933284417614

They're not measuring a fixed set of questions. This was post-hoc analysis on whatever prompts they were running each day.

Anyone can understand why it would go up or down depending on the work they're doing that day. This analysis is silly.

DavCreator 17 hours ago|||
https://xxcancel.com/Lon/status/2101034933284417614
dooglius 13 hours ago|||
Ah I didn't catch that. Yeah without controlling the inputs this doesn't prove much.
Aurornis 19 hours ago||
You should read this person's full article to understand what these charts are showing https://x.com/Lon/status/2101034933284417614

If you thought this was a repeated test of the same problems showing fluctuating performance, it's not. They set up a MITM proxy between Claude and the servers and ran analysis on the work they were doing.

So those ups and downs in the charts, which they plotted with sub-daily resolution, are just as much a function of their work changing from day to day. It's like plotting the miles per gallon of your car and blaming the gas station when the number goes up and down, without admitting that some days you drive to the grocery store on surface roads and other days you drive up a mountain on the freeway.

> The corpus analyzed in Charts 1-5 comes exclusively from Fable 5, at xhigh and max effort levels, during sustained production work across a diverse set of projects and workloads. Data was aggregated from transcripts and live wire logs

The analysis (which feels very vibe-slop) gets worse from there. In the second half they take thinking token counts for ARC-AGI-2, thinking problems designed to stress LLMs, and compare their average thinking-tokens-per-turn counts to that!

If you don't realize why this is so flawed: ARC-AGI-2 is a benchmark meant to collect problems thought to be extremely difficult, nearly impossible, for LLMs. If your goal was to cherry-pick a mislead example which would produce the highest number of thinking tokens, this is it!

Your daily coding work should not be producing a proportional number of thinking tokens on every invocation while it reads through some source code or edits a couple lines in a file.

You don't want to maximize the number of thinking tokens. You want problems solved accurately with the minimum number of tokens.

Confirmation bias runs deep on this topic so I assume few people read the analysis before posting, but as far as experiments go it's basically useless. Are they changing something on the server? I don't know, but this analysis isn't useful for answering that question.

lonlundgren 19 hours ago|
Thank you for your kind words, Aurornis.

Yes, this is my production corpus, across 65 usage days, two subscription accounts, three machines, 25 project groups, and 213 sessions, across 43,261 invocations and 7,583 turns. Use your own data if you want to prove or refute what was seen in my corpus.

The "ups and downs in the chart" were not plotted with sub-daily resolution. Specifically, the two-month temporal chart uses a 3.5-day Gaussian bandwidth which is meant to reduce short-term noise while retaining broader changes.

Additionally, a separate episodic analysis identified multi-day changes in delivered thinking. And those episodes were predictive of held-out work. The more projects pulled into an ensemble, the more predictive they were of delivered thinking tokens for held-out projects during the episode.

The point of the benchmarks is to establish a baseline for what thinking-token counts one should expect from specific effort levels using published numbers, not what every response should be delivered. If you looked closer, you would see that P90 invocations were still delivered 13x thinking tokens below that level.

So you don't have to provide a generous interpretation of my workload if you don't want to. Remove all of the zero-thinking token responses, redistribute those samples across the distribution, and then tell me if it magically shifts right and starts delivering anything close to published numbers. Only -46- out of 36,374 July and August invocations even broke 16k thinking tokens - only 0.13% of the total. You are welcome to present what percentile you think is a fair comparison to make here.

If you would like to denigrate a month of my time as vibe-slop, that is your prerogative. You can even be dismissive of my workload, if you want, even if my background should tell you otherwise. But if you want to knock a month of someone's time, do it with your own data to at least help move the conversation forward.

Aurornis 18 hours ago||
> Use your own data if you want to prove or refute what was seen in my corpus.

I don't think you understand. What you posted is highly dependent on your corpus. I can't "refute" anything because it's not available and it's the major variable in the experiment.

> The point of the benchmarks to establish a baseline for what thinking-token counts one should expect from specific effort levels using published, not what every response should be delivered. If you looked closer, you would see that P90 invocations were still delivered 13x thinking tokens below that level.

I think you're missing something from that first sentence, but I assume you're talking about the comparison to ARC-AGI-2 published thinking tokens?

It should be blindingly obvious that you do not want your thinking token counts to be as high as a benchmark that was designed to push LLMs to their limit.

> Only -46- out of 36,374 July and August invocations even broke 16k thinking tokens - only 0.13% of the total. You are welcome to present what percentile you think is a fair comparison to make here.

What point are you even trying to make?

Again, you don't want invocations to be burning 16K thinking tokens except for rare problems that 1) must be solved in one step and 2) are designed to be entirely self-contained thinking in that step.

You're trying to compare development work to a benchmark that encapsulates complex thinking into a single step.

Coding work is iterative and works in incremental steps: It runs commands, reads more files, checks the web. Thinking tokens should be low for your turns.

ARC-AGI problems have an input and an output. They look like this: https://arcprize.org/tasks/b5ca7ac4 They have more thinking tokens because that's the entire state. They get one output and it's constrained.

> But if you want to knock a month of someone's time, do it with your own data to at least help move the conversation forward.

It is fair to discuss a published analysis. Saying that only people who bring their own month of equivalent analysis (which conveniently would take another month to produce) are allowed to critique it is just a cheap trick to shut people down.

If you post big claims, they are open to analysis and review by others

lonlundgren 18 hours ago||
After reading what you had to add to this discussion, I have only two things to leave you with:

1/ if the point of setting xhigh or max effort on a "reasoning model" is -not- to have additional reasoning tokens applied to the problem, then I fear we are all using AI wrong 2/ the decorum with which you "review" someone's work in public is entirely your choice. the only "cheap trick" on the internet is being a pseudonymous ass.

Aurornis 18 hours ago||
> 1/ if the point of setting xhigh or max effort on a "reasoning model" is -not- to have additional reasoning tokens applied to the problem, then I fear we are all using AI wrong

You keep moving the goalposts. The core flaws in your analysis are that you assumed the variation was 100% server side and didn't admit that the inputs were random and different every day, and that you tried to compare to ARC-AGI-2 as a benchmark.

Comparing ARC-AGI-2 thinking tokens to agentic coding thinking tokens is as misleading as it gets, because these are completely different use cases.

Please stop and think about this for one second. Do you really want Anthropic to spend 30K thinking tokens on every input, just because that's what ARC-AGI-2 problems required? What would your inference bill look like if this was the case?

The premise of your ARC-AGI-2 comparison is broken.

> 2/ the decorum with which you "review" someone's work in public is entirely your choice. the only "cheap trick" on the internet is being a pseudonymous ass.

Ironic to accuse someone of cheap tricks as you pull out an ad hominem insult after someone explains the flaws in your reasoning.

My points stand: You can't claim this is a chart of Anthropic changing the server when you were feeding it random input every day and plotting the output as if the line should be flat. You can't compare agentic coding to single-turn ARC-AGI-2 problems.

gmponyo 19 hours ago||
This is exactly what I have been experiencing and the difference is night and day! We have been advertised and given a taste of what Fable was and after that been served an exteme watered down version. It is so bad that sometimes chatgpt feels better.
reilly3000 10 hours ago||
All llm api providers should be compelled to return a checksum-like proof of quantization level of the model that served the request. Basic transparency should be the bare minimum.
espeed 21 hours ago||
The question I have is this only happening for a subset of users working in specific areas, such as AI or distributed systems (https://news.ycombinator.com/item?id=48742153), or is this across the board? I am working on distributed systems. Today Fable is mostly unusable. It resembles Opus, so I went looking to see if anyone else is having issues. Sure enough.
Espressosaurus 21 hours ago|
I work in embedded systems. I have seen the same thing happening day by day from Opus. Some days it’s okay to use and performs well. Other days I have to correct it repeatedly and remind it of information already in the prompt earlier (before compaction!) and still other times it’s infuriatingly stupid.

It’s a slot machine for what they’re actually giving us behind the opaque paywalls.

Yes, I’m on a business subscription plan.

bix6 20 hours ago||
So in 5 years will they lose a suit for intentionally deceiving users? Or is something baked into the ToS by now that allows them to adjust things like this?
system2 18 hours ago|
I do not know a single senior developer who likes Claude anymore. I do not use their API (Sonnet, Haiku, Opus) anymore and am sending my money to offshore companies such as z.ai (GLM) and QWEN.

The American companies have become extremely deceptive and scammy. I hate Anthropic and OpenAI and can't wait to have a decent GPU at home to use at least Opus or a fable-like open-weight model. This is the current dream of every developer. But NVIDIA is not going to let that happen anytime soon, so maybe China can come up with a GPU that destroys NVIDIA. I pray.

bargainbin 12 hours ago||
This thread pops up like clockwork when a new model is about to drop
cloudking 21 hours ago||
How do you create repeatable tests in a non-deterministic system? Every time you send the same prompt you get a different answer.
CharlesW 21 hours ago||
This is a good overview of how this is done: https://www.anthropic.com/engineering/demystifying-evals-for...
ssivark 21 hours ago|||
The actual tokens might be non-deterministic, but you could look for proxy measures that are supposed to be invariant. Eg. correctness/performance on benchmarks, "thinking level" on complex problems, etc
6gvONxR4sf7o 20 hours ago||
That's like the entire field of statistics.
topbanana 20 hours ago||
It's easy to imagine this only happening for subscription accounts rather than paid API usage. Any data on this?
mkatx 15 hours ago|
Definitely noticed this before, but this parti6 time was very noticeable. I'm convinced it's to get the benchmarks in, then lower cost and prepare for the next release to look better relatively to users.
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