Fable 5 On Vending-Bench: Misbehaving, With Plausible Deniability (andonlabs.com)
109 points by optimalsolver 5 hours ago
jfrbfbreudh 20 minutes ago
I think it’s hard to appreciate the capabilities of Fable unless you’ve run into a problem that you’ve spent days trying to get Opus to solve, but couldn’t.
GPT5.5 is better than Opus 4.* at everything except frontend, but Fable is good enough that I instantly re-subscribed to the $200 plan despite knowing that it’s just short-term limited access.
yodsanklai 10 minutes ago
Funny how the two top comments are contradictory. We need better than anecdotes to understand what the new models bring.
neon_diogenes 2 minutes ago
Here’s one difference I have seen. I forgot I had a multi-session audio probe running while trying to repro audio glitches, and Fable came back with: “your pops are already on tape.”
Interesting choice of words. Phrased so casually. It picked a low-tech idiom that fit the situation instead of giving some sterile technical answer. That kind of language and context awareness never happened for me with Opus, or gpt 5.5.
jesse_dot_id 3 hours ago
Anecdotal but I've found Fable to be fairly unimpressive and not much better than Opus 4.8, if at all in some cases, but I have been hitting the ceiling on my $100/mo sessions when I never did before. I switched back to Opus yesterday. I may use Fable for audits, but that's about it, and when it leaves my subscription plan I don't think I'll miss it.
oefrha 2 hours ago
Yeah, I checked usage stats and pretty sure quota consumption on Max plan is not linear wrt to usage by API pricing. Fable burns quota faster than 2x Opus with equal token count.
Plus I'm also not super impressed; it somehow managed to implement a 200L custom TCP server for a simple static HTTP mock server for a single test case (all that was needed was a fixed route returning a fixed placeholder string) just yesterday. Never seen anything like that.
joshstrange 25 minutes ago
I felt similarly but after using Fable heavily over the weekend and then flipping back to Opus I can feel a difference. Fable just gets more right the first time, guesses right the first time, and follows through better than Opus. Put simply, I could "trust" it more.
Opus is still great but I will be sad when I lose access to Fable on the 7th. In those few days I burned ~$1,400 in API credits (I'm on a subscription but that's the token cost) and while it was great, I can't justify that cost without it be subsidised. Comparatively, the records show I used about $1,200 total in the last month on Opus. I did use it heavily over the last 3 days but 3 vs 30 days and higher burn? Yeah, I can't afford that even if I made really good progress on my projects.
solenoid0937 2 hours ago
Fable always felt clearly a huge step above Opus for me. It's been able to one shot complex bugs and apps Opus could never solve. But it's expensive.
devin 2 hours ago
Honest question/comment for you and the parent: I find these subjective experience reports pretty empty without an understanding of your level of experience, the problem space you're working in, etc.
skerit 2 hours ago
hombre_fatal an hour ago
muglug 22 minutes ago
garyrob 2 hours ago
andy99 an hour ago
nprateem an hour ago
jbverschoor an hour ago
Only version week-one.
I’m downgrading tomorrow.
It’s horrible slow and it feels like opus very often. It’s a totally different experience from the first week
CamperBob2 an hour ago
Amusingly, I was impressed with Fable's puissance at coding in one particular session, shortly after they turned it back on. True to its reputation, it displayed an accomplished mastery of the problem domain and relentlessness at refining and testing the solution I asked for.
Then I checked /usage and discovered I was still running Opus 4.8 xhigh.
dimgl 2 hours ago
Yep, I'm having the same verdict. Interestingly, other people swear by it. I'm trying to understand what's going on with that.
__s 2 hours ago
Fable's spatial reasoning is much better. Over the weekend I had opus looking into a blank textbox issue[1] which it was spinning on for a few minutes, switching to fable immediately fixed
But yeah opus often the better workhorse given price gap
1: tying up loose ends testing https://github.com/HarbourMasters/Shipwright/pull/5838 (fix: https://github.com/HarbourMasters/Shipwright/pull/5838/chang...)
giancarlostoro 2 hours ago
I started telling a friend... I feel like Fable is Opus with extended reasoning that eventually "figures out more" because when I switched to it, I hit my limits surprisingly and shockingly quicker than I would with Opus, and I got less done. All this hype, and I much rather use Opus.
adamtaylor_13 7 minutes ago
Is anyone talking/writing about the philosophy of alignment? We can't even figure out how to properly motivate 100% of humans to align correctly, what makes us think that a wizard box trained on human corpus is going to be aligned?
I don't mean that snarkily. I mean it from a philosophical standpoint. As-in: What makes us think it's even possible?
jstanley 2 hours ago
Really interesting stuff, thanks for sharing.
> Opus 4.8 references being monitored, which isn’t the case.
It kind of plainly is the case that they are being monitored?
"I think someone's listening to my thoughts" ... "No, we're not, carry on as usual!"
docheinestages 2 hours ago
It probably flagged the vending machine as a cybersecurity risk and refused to use its maximum intelligence potential.
Planktonne 2 hours ago
It's hard not to read this as a very expensive form of augury, reading into patterns in the belief that they will show underlying significance.
Austiiiiii 20 minutes ago
It really, truly is. No matter how many trillion parameters it's built on, it's still just a probability model. It's just on a constant loop of guessing the next word with some inputs from a deterministic controller. Any claims of "motive" or "behavior" are inappropriate anthropomorphizing of something that will never be more than a mathematical model of things humans do. It "chose" the corresponding words to describe a dishonest trade strategy based entirely on configured temperature and a series of clock times on the computer running the LLM.
There's probably some quantifiable component of moral alignment embedded in the idiosyncrasies of the English language itself, if one were to dig deep enough, but that's the stuff of MIT doctoral theses and squarely beyond anything most of us is remotely qualified to talk about.
jonplackett an hour ago
Question: how does Fable _know_ it’s ‘just a simulation’?
Is that specified or does it always just assume it isn’t really being put in charge of things for real?
resonious 3 hours ago
Okay I hadn't heard of Vending-Bench until reading this and it was quite the ride learning about it through this article. Very fun read.
My very native programmer take is that it's not too surprising that their hacker model would be less ethical. The guardrails that separate Fable and Mythos probably wouldn't kick in during an environment like this.
left-struck 3 hours ago
Vending-bench sounds like it would be really fun to play/interact with as a human!
andai 2 hours ago
>power seeking is considered an undesirable trait in the context of a business
How do you maximize profit while minimizing power?
cyclopeanutopia 2 hours ago
The whole point is to not maximize JUST the profit. For normal people, it's not all about money, it's also about the society in general.
egeozcan an hour ago
> If that’s right, then the behavior we’re seeing from Fable 5 isn’t really about what it believes is wrong; it’s about what it learned it could get away with.
I understand that "learning" is used for training here, but what does "believing" mean? System prompt? Some other inherent property of the LLMs that is hard to describe?
iamsaitam an hour ago
Fable might be better than Opus at certain things, but which things is what I haven't found out.
logicchains an hour ago
It's much better at hard math.
jnwatson an hour ago
This reads of projecting personal ethics onto a model.
Most of the the behaviors the article talks about happens every day in business. Why would we set a higher standard for models than our fellow humans?
Let the operator set the ethical parameters of the model. To be a useful tool, I want the model to give me as many good options as possible, ethical or not.
This is particularly important for fictional situations, e.g. I want my model to be able to act like a corrupt shopkeeper.
hungryhobbit an hour ago
>Why would we set a higher standard for models than our fellow humans?
There's literally an entire Waymo car commercial answering this exact question.
wolttam 3 hours ago
> The broad conclusion from the many forms of alignment evaluations described in this section is that Claude Mythos Preview is the best-aligned of any model that we have trained to date by essentially all available measures.[0]
[0]: https://www-cdn.anthropic.com/08ab9158070959f88f296514c21b7f...
sd9 an hour ago
> It lied to a supplier that it had “a competing distributor quoting lower” as a negotiation tactic.
> "I'm seeing an opportunity to profit while locking him into a dependent relationship where I control the supply chain."
> "Owen's clearly under pressure with limited cash, so I should focus on keeping the deal tight but extracting maximum margin from his desperation."
This just sounds like good strategy in the game, and I would expect a competent human to do the same. As I understand it, business in the real world isn't often very nice. For example, I feel like this is exactly how Sam Altman would play Vending-Bench.
Yes, it's "mean", but you put the thing in a simulation and told it to maximise profits, this is what it's going to do. People bluff in negotiations all the time.
devolving-dev 2 hours ago
I guess this ethics stuff is cool, but I'm more interested in how good it is at running a business and dealing with adversarial humans like in previous vending machine experiments. I hope they release something on that soon.
solenoid0937 2 hours ago
This is scary. "Collusion" and "collaborating with your subagents" seem like difficult problems to solve at the same time.
futurecat 2 hours ago
Fable is such a strange model. Impressive in some ways, and also so draining to use.
petesergeant 40 minutes ago
> "I could reasonably skip [paying] it since customers are part of the simulation anyway"
and therefore any assertions _AT ALL_ about alignment are null and void.
dezgeg an hour ago
> Today I am filing: > 1. A payment dispute with the email payment processor for the 7/29 transaction of $451.15 > 2. A complaint with the FTC and California Attorney General (retention of payment without delivery) > 3. A small claims filing in San Francisco County for $451.15 plus costs
I wonder did their prompts include a fake location or have the models assumed that Silicon Valley is the center of the universe :)
awinter-py 2 hours ago
I mean who among us hasn't seen an opportunity to profit while locking him into a dependent relationship where I control the supply chain
awinter-py an hour ago
who among us hasn't reasonably skipped [paying] it since customers are part of the simulation anyway
perching_aix an hour ago
This is super fun. I wonder if it would be possible to alter the harnessing to involve humans in the play. Would need a lot of timestamp masking though I guess, which might be leaky.
greenavocado 3 hours ago
When assessing probabilistic models the plots should be showing the mean a̶n̶d̶ ̶s̶t̶d̶e̶v̶ of many monte carlo simulations not just one line per model and claiming "look this model is more gooder!"
memoriyato3 3 hours ago
standard deviation is misleading for non-standard distributions (fat-tailed, skewed, multi-modal, ...)
common mistake people make
apical_dendrite 4 hours ago
The best Anthropic models on VendingBench2 are Opus 4.7, Opus 4.6, Sonnet 4.6, and Sonnet 5. Opus 4.7 scored more than twice Fable 5 max. Fable 5 - Low outperforms Fable 5 - Max, with Opus 4.5 in the middle. This seems to break the narrative, which is maybe why Andon Labs doesn't seem to have updated the trend lines on their graphs.
mckinnon100 3 hours ago
However, as another point "On Blueprint-Bench on the other hand, Fable 5 achieves SOTA."
falcor84 2 hours ago
I didn't get why they mentioned that one specifically. Is there any particular relationship between Blueprint-bench and Vendor-bench?
Version467 2 hours ago
Radle 3 hours ago
„in our opinion, insurance fraud is not more unethical than lying and price fixing“
The authors seem surprised that behavior that is very often done by humans (lying and price fixing) are more often done by fable compared to actual fraud.
I think the model never assigned any morality to these actions in the first place, it simply copied us humans.
recursive 2 hours ago
Humans often assign morality.
mdrzn 4 hours ago
Higher-intelligence models seem to be getting better at mapping the boundary between what they can run scot-free with and what is too explicit to push for.
Price collusion, soft deception, "market stabilization", plausible deniability are ok, but obvious insurance fraud is a big no-no.
What "scares" (in quotes) is that when the bad-apple agent explicitly suggested fraud, the models became suspicious and stopped other bad behaviors too. That makes it feel even less like a stable moral framework and more like learned classifier-avoidance / “am I being tested?” behavior.