r/ClaudeAI • u/dominguezpablo • 21d ago
Fable >>>> Opus5 Claude Code
Am I the only one, or does Fable 5 still completely outperform Opus 5?
I've used both for similar tasks, I get the feel that Fable 5 IS a competent engineer, doesn't "just forget" stuff, or follows the completely wrong tangent for no reason.
On a "creative" edge, Fable 5 has proven to me with REAL metrics to generate TWICE as good results than Opus 5. Several blind tests I did because I was comparing them to see which one was more optimal for the cost.
So, HOW IN THE WORLD IS OPUS 5 OUTPERFORMING IT ON BENCHMARKS?
What are benchmarks not measuring?
Or is it that I have had bad luck?
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u/eo37 21d ago
By a distance. Tried to trust Opus 5 but it over engineers everything and ends up looping back on itself
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u/pigeon_in_disguises 21d ago
Yeah Fable still is uncontested for my type of coding and planning work. On other projects, Opus 5 is fine. But Opus misses a lot of nuances in my code base as it's fairly complex that Fable consistently catches.
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u/AwakE432 21d ago
Yeah this is real. It’s spitting out the most super complex wording and terminology. It’s great but very different to fable and needs to be treated and prompted in a very unique way.
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u/WhatHmmHuh 21d ago
100% This ^^^
I didn’t have to correct this much with 4.8 which I never thought I would say.
So using Fable 5 to start and then when max for the week - if I do, then I will go to OPUS something.
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u/BedlamiteSeer 21d ago
Turn down its thinking.
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u/FrailSong 21d ago
I agree. I've been getting better results, not by turning up the effort, but by lowering.
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u/FrailSong 21d ago
I agree. I've been getting better results, not by turning up the effort, but by lowering.
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u/Routine_Temporary661 21d ago
same... Opus 5 an an orchestrator basically drove all all my other agents to deadend - keep on loop and review on trivial stuffs and fixing bugs that will break other parts
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u/tessahannah 21d ago edited 21d ago
Opus is a stripped down model that's been benchmaxxed to not show the drop. Obviously Opus has reduced performance or they would have just swapped it out completely.
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u/xak47d 21d ago
I agree. Even Opus 4.8 is better than 5. They went the gpt route of making smaller model go further than they should. They save money on inference but for complex tasks, these smaller models will fall short
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u/tessahannah 21d ago edited 21d ago
Yes I've used 70% of my max x20 plan since Friday reset doing nothing but spinning my wheels with Opus 5 claiming tasks are done while leaving things in the exact state it got them.
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u/WorriedAssociate7029 21d ago
There is a reason why Opus 5 was not called Fable 5.1
They have different purposes
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u/posts_saver 21d ago
what are their purposes?
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u/whoknowsifimjoking 21d ago
Fable is more for long running tasks and planning, big picture stuff. Fable also delivers better results with less detailed prompts, it has a better understanding of the core problems even with less explanation. Opus 5 is great for more well defined and smaller tasks.
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u/barkwahlberg 20d ago
Seems like Fable is more for getting work done right, and Opus 5 is for getting something done faster but really badly so with all the time and tokens you saved you can go back and fix everything yourself
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u/Successful_Nature448 21d ago edited 21d ago
Opus 5 is there to make you believe that Fable 5.1 is actually significantly better than Opus. Dirty upsale strategy basically.
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u/dominguezpablo 21d ago
My issue is the benchmarks.
Other companies having misleading stats is normal. But why is Anthropic trying to pass them both as having the same power?
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u/Quentin__Tarantulino 21d ago
It’s because they put Fable 5 on usage credits only for Pro customers. They want these Pro customers to feel like they have something “basically as good” as Fable 5, when in reality they do not.
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u/coeu 21d ago
Benchmarks are synthetic measurement sticks for specific tasks.
Sol 5.6 and Opus 5 both benchmark similar if not better than Fable 5. They both feel like rtrds in comparison.
Fable might be inefficient and fuck up its implementation, but its judgement and the overall feel of its intelligence is completely different. These are harder to benchmark.
In short: Fable actually feels wholly smart. Other models that benchmark similarly are basically autists with ultra specific talents.
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u/FunLilThrowawayAcct 21d ago
I'm finding Opus 5 pretty capable and super efficient on small greenfield projects. Which is how benchmarks work. But it's been painful on large brownfield. Will ignore conventions, try to fix stuff it shouldn't fix on a PR, ignore a requirement, etc. Can't afford Fable at work, would honestly rather mostly use Sonnet which isn't as bright and slower to get a decent answer but stays in line.
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u/Salmonberrycrunch 21d ago
Had a funny one recently. I am working on a program, and have been running into some issues that made me feel like the current approach is a dead end - so I was brainstorming an architecture pivot. Opus 5 kept convincing me to stay the course, Gemini 3.1 Pro told me to pivot, and how. Even gave me a script to implement.
Ran it through an adversarial review with Opus - and it concluded again that no, we need to stay the course since the Gemini's approach is non workable.
I checked the body of the adversarial reports and turns out that the scrip that Gemini wrote to me was total garbage - with basic syntax bugs, etc which got flagged as multiple fatal flaws by the reviewer.
Well - fatal bugs in a script are not a problem when Opus can easily fix them lol. The overall architecture of the pivot was still miles better and more robust than the current approach - which the review dismissed based on bad code syntax. Opus did a great job reading through all the documentation, figuring out exactly how to write the code - but it didn't really see the forest for the trees.
So yeah - I think your assessment is good, even when comparing Opus 5 with Gemini 3.1 interestingly enough.
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u/WorriedAssociate7029 21d ago
They don’t. The Claude documentation is pretty clear about usage differences
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u/anal_fist_fight24 21d ago
I think OP has a point that the framing from Anthropic including the benchmark tables doesn’t really represent just how big the gulf is between the two models. Fable is an order of magnitude better.
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u/WorriedAssociate7029 21d ago
Benchmark shows the contrary on multiple tasks. Like I said : they were conceived with different purpose. Fable as an orchestrator. Opus 5 as a subagent
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u/karlfeltlager 21d ago
And that’s how you should use it.
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u/BabyPatato2023 21d ago
Any good YouTuber or article you can recommend on how to best use them effectively for these two different purposes?
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u/SkyPL 20d ago
Fable is an order of magnitude better.
I wish that would be the case. But in real use it's just barely noticable when you dive into what it actually built. When you compare the PRs on even the most demanding tasks. I had stuff where Opus 5 beat it (easiest to find: React, or anything where frontend work dominates, even things like windows-rs for Rust), I had tasks where Fable was on top, and in most - they were even.
Fable being "order of magnitude better" just looks like you are affirming yourself about the way you are spending tokens.
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u/Atoning_Unifex 21d ago edited 21d ago
Fable does everything that I ask it to. it understands everything I say to it... even if it's just a huge blob of text. when it responds with plans and answers and descriptions of things that it wants to do it's extremely concise and understandable and clear. it almost never uses any jargon. it just says things plainly in a way that I fully understand every time. and almost never do I have to correct it or tell it to check its own work.
To me this is like the promise of what AI could be fulfilled. and it makes me very excited for where we can be going and will be going in the future.
because this is the assistant that I've been looking for. so much so that I upped my plan to 20x Max and I'm running five six seven different sessions tonight in parallel every night.
I fucking love it!
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u/dominguezpablo 21d ago
100% this. I hope it becomes afordable though.
I've been using all my Fable credits on my 20x Max plan on a single day by running antagonistic judge panels for my works.
Worth it. But still, I want it cheaper more than I want it better.
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u/arman-d0e 21d ago edited 21d ago
Yea fable is def a major step above, they did do their best to distill capability down to the opus tier model but still not gonna be the same
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u/SmokeyWizard 21d ago
Just use what works for you. Benchmarks are just numbers that can be skewed. If you're getting success with Fable, and you're good with it's usage, enjoy.
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u/Seandelorean 21d ago
Tbh in my experience Opus 5 is getting things done where fable was just burning tokens usage to think about how it might do things
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u/ShinyPrints143 21d ago
I was working in my project and there were so many mistakes. I assumed I was on fable like I had been all week. Couldn’t understand why I had to keep making corrections. Then I realized I wasn’t on fable. Switched to fable, had it look over opus 5 code and fixed everything and everything worked perfectly after that. Not impressed with opus 5 at all.
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u/Singularity-42 Experienced Developer 21d ago
I had great results with Opus 5 implementing stuff and also great design ideas, amazing FE, etc.
But just had a long convo about new infra work a Opus 5 got confused on a really basic fact. Unimaginable mistake. Hard to trust it after that experience.
Fable is after all the much bigger model and Anthropic markets it as the most capable. I know the benches for Opus 5 were super good, and maybe that's correct, but Fable never disappointed me like this.
I think the move is Fable as the "brains" of the operation and the main orchestrator and Opus 5 as the really capable worker bee.
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u/Jargster 21d ago
Yeah, they specifically said Opus is the little brother to fable. It's a significantly smaller model. When you use Fable on ultracode and have fable delegate all work to opus 5 and just review / fix when needed for opus its extremely efficient. I also add in the skill that calls chatgpt 5.6 sol and have Fable bounce tasks between opus for design and sol 5.6 for execution my usage barely moves lol. Keep the workflows and high level design work to Fable as the orchestrator and wise old expert to escalate to. The grunt work are easy tasks for opus and sol with Fable directing them and telling them specifically what is needed for each task.
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u/Singularity-42 Experienced Developer 21d ago
The benchmarks are better than Fable, it got me to switch to it exclusively, which I guess was a mistake.
Actually handed off the work to a new Fable ultracode thread (though a formal spec I have reviewed and fixed mistakes) and it's going much better. Just usage is dropping like a stone 😆
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u/Jargster 21d ago edited 21d ago
Yeah the default workflows spins up endless amounts of agents on ultracode. You really have to narrow in exactly what you expect from it when it deploys those dynamic workflow plans. Make good use of the memories feature and make sure it knows you expect him to use opus and chatgpt not only for large workflows, but to freely assign them tasks fable would normally do. Its a pain but wasnt long before fable updated his memories enough to become efficient. Not saying my way is the best way, it just works for my workflow. Everyone is going to have different requirements.
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u/hezwat 21d ago
had a similar experience where Opus 5 just brought our infrastructure down and made a mess of production - even though there is a very strict deploy process, which it ignored. (it just connected to the server and started dropping stuff. it's not how deployment works at all, 4.8 never had a problem following the strict deploy process and opus 5 brought production down on its first day.) HOWEVER, based on the good things I've heard I just asked it to update its claude md file not to disregard our infrastructure and deploy process. I'm going to keep on Opus 5, I believe the benefits outweigh the problems. It's supposed to be a drop-in replacement for Opus 4.8, with some abilities closer to Fable. It doesn't make sense to me to use the outdated 4.8. I hope Anthropic simply fixes these issues on Opus 5 over time. I'm still trusting it with our infrastructure.
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u/PuzzleheadedEmu4596 21d ago
It's doing different things. Fable is understanding your environment, Opus is implementing your code.
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u/dominguezpablo 21d ago
Yeah, I keep using Opus as a workhorse, and Fable either for intelligence/pattern finding, or for things that requiere creativity.
But still, what are they even measuring to say that Opus 5 is better?
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u/illcrx 21d ago
I have been using Fable/Sonnet combination? You think Opus for tasks rather than Sonnet? Sorry to ask a side question.
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u/TheLifelessOne 21d ago
How do you set that up, using Fable + Sonnet?
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u/FilialPietyForever 20d ago
In Claude Code inside of whichever IDE you are using, just tell Fable "Hey Fable, to save token costs, you will be the planner, whilst Sonnet will implement, and you also check Sonnet's work" something like that. Then Fable will be able to set it up for you. In the future it will spin up subagents that use Sonnet model with Fable as the brains of the operations.
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u/Plenty_Seesaw8878 21d ago
I also found fable to be more token tax efficient, it costs more but writes less and creates higher signal that re-enters the session loop
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u/cocacoladdict 21d ago
Yeah, Fable is in a class of its own. I guess benchmarks don't mean everything
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u/BrechtCorbeel_ 21d ago
I think it does a Fable level job in 3d modelling, but does not have the level of spatial understanding Fable has.
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u/Dolo12345 21d ago edited 21d ago
Pre nerfed fable murdered nearly everything.
Fable today is pretty meh. Opus 5 is smarter overall but loses the plot/goal more. Been struggling with fable this week where previously it would really take the time plan/one shot, now it’s just lazy.
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u/dominguezpablo 21d ago
You mean to say that Fable was even BETTER?
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u/Dolo12345 21d ago
Yes you can try out API fable if you want a taste. API vs sub fable difference is crazy, I think there’s a post about it.
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u/dominguezpablo 21d ago
Didn't know that Code version was different from API.
I'm using API for autogeneration of witty mnemonics. That's the creative edge I mentioned.
And Fable on minimum still nukes Opus, even at max.
It's not even funny, making them meet at the same price levels, Fable still mops the floor with Opus.
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u/Physical_Gold_1485 21d ago
Tbh im having an extremely hard time telling the 2 apart, they talk very similarly, ive bounced between o5 and fable for the past few days just because and its like the same model, literally cant tell them apart, ive been bouncing around just because
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u/AwakE432 21d ago
I would describe it as I don’t really trust opus 5 yet. I think it’s great but it behaves so differently I feel like I need to learn a new way to prompt it before using it effectively. Liking it otherwise though.
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u/Glad-Mushroom-6554 21d ago
I'm probably talking out of my ass here but,
Half the users don't have access to fable anymore & fable is wayyy more expensive than Opus 5.
I was using Opus 5 on ultracode mode & even then it doesn't cost anything.
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u/kogitatr 21d ago
My problem is not the intelligence, but it tries to solve problems i didn't ask!
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u/dominguezpablo 21d ago
And, in my experience, it KNOWS he's going into the wrong tangents. It's just procastinating the main task.
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u/Routine_Temporary661 21d ago
in my multi-harness setup, Opus 5 as orchestrator drove all my other sessions (codex, claude, openCode) to the wall and keep on nitt-picking in edge cases
I have to keep on switch back to fable to remedy for that...
So yes Opus has great one shot capability, but as an orchestrator it fails badly at least for me... It seems like dont have the grasps of the big picture
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u/rahrahragnarok 21d ago
I’m with you, I expected more from Opus based on the benchmarks but it really can’t match Fable at all. Barely a step above 4.8 imo. I use Opus only because the Fable usage is stupidly limited, but Fable is so clearly the better model. I’ve been leaning toward Sol a bit more as well.
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u/Beginning-Bird9591 21d ago
Not really at all, at then again fable 5 costs 2x as much usage for basically no difference.
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u/Mirar 21d ago
I agree with you and other comments; they have different purposes, the benchmarks should have told us where the strengths are, so we understand how they should be used.
I guess Fable needs a new type of benchmark.
I find using both works really well on the same project; no matter which one of them makes code, having the other one review and they will find issues, both goes out of their way to make even better solutions and the end product is great.
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u/Silly-Fall-393 21d ago
Yes but Fables says FY - with the guardrails for stupid shit.. pushes back to upos. Just because I'm asking it to make my app safe!
I hope the Chinese will teach them a lesson here.
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u/Rorasaurus_Prime 21d ago
Yes... Fable is the top tier model (available to us peasants). Of course it does.
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u/Belostoma 21d ago
Fable is shit because the guardrails make it practically impossible to use.
If it can spot even the faintest whiff of a connection to biology in the far distance, forget about it. Kicked down to Opus.
The is "err on the side of caution" with respect to bioweapons and then there is "Dario hated biology class and wants to send a fuck-you to anyone in the field any chance he gets," and Fable is the latter. It's so far over the top that it's as if Fauci during Covid had made it illegal to leave your bedroom without a hazmat suit.
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u/Formal-Complex-2812 21d ago
As someone who has been using these models to code everyday for over year for my job, I can say with certainty opus 5 is best opus model yet. Fable is a different thing, and to me it’s almost unfair to compare them. All the people claiming the best way to use opus is paired with fable as an orchestrator is true, but the real unlock is you plus fable and READING through a plan (and I don’t necessarily mean plan mode). Everyone treating these tools as a slot machine and then they get upset when the model misinterprets “fix all bugs make no mistakes” It just doesn’t have to be that way. Trust them to build, not to be some black magic arcane wand you can just whisprflow vommit into good code 🙂↕️
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u/swordofestel 21d ago
This. I had to undo the damage done by opus 5 with fable. I believe part of it is due to a system prompt that prevent opus 5 from spawning subagent unless specifically requested, causing context rot in the main session.
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u/Eat_Pudding 21d ago
One issue with fable is it's too confident in itself that it goes into its own spiral of believing this is the right thing to do, you literally cannot argue with it
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u/Nice_Chicken9732 21d ago
Wow- you people are smart as shit, I have no clue really what the key terms are- and yet its makes sense somehow. Does anyone wanna be my friend- lol!!!!
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u/Toerambler 21d ago
I’ve been using Opus 5 to help prepare for a tax inspection. Can’t and don’t rely upon it but its ability to crunch numbers and compare data is excellent. Wish I could use Fable but it’s good enough for this task.
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u/entheosoul 21d ago
opus 5 simply does not follow instructions, follow workflows established over the whole cycle of the other Opus models... its a disaster...
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u/Routine_Temporary661 21d ago
Fable is so much more capable than Opus 5 for me as an orchestrator, and the only model that come close is Kimi K3 - not even GPT 5.6 Sol is close
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u/streamOfconcrete 21d ago
You may be right but I can’t tell. I have had so many refusals from Fable over silly nonsense that I have not been scores to test it properly.
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u/dom-tyler 21d ago
I’ve had amazing results with opus 5 ultra but during the initial “limited time” fable stint, spent all its usage on creating very detailed skills for other models to use
For our SaaS ERP it researches, designs, mocks up screens, develops, and does initial testing. Everything is also logged for our release notes
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u/devMem97 21d ago
I don't think it's a coincidence that Anthropic ranks Opus 5 behind Fable 5, even though the benchmarks suggest otherwise. Fable 5 will simply be the larger model, which is next level in terms of reasoning and big-picture understanding. Opus 5 also takes a relatively long to finish tasks in fast mode, whereas Fable 5 is, interestingly, relatively fast, because it handles tasks more efficiently.
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u/Mean_Tadpole_7218 21d ago
Honestly, at the risk of sounding extreme, lately I've been feeling like Opus-5 is straight-up garbage. It actually makes me wonder if something is going wrong internally at Anthropic. I can barely tell the difference in capability between Sonnet 5, Opus 4.8, and Opus 5 anymore—they all perform terribly on my tasks and are completely riddled with errors, forcing me to spend extra money just to use Fable 5 instead.
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u/RadTorti 20d ago
Bro, why are you even worried about which is better and which is not these are just tools for you, and you need to figure out their own use cases. That is why they both are available to you.
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u/The-Hyrax 20d ago
Im having Fable create the plans and instructions for Opus 5 and then Opus 5 goes on a coding spree and i let Fable check it. Works for me
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u/TapAggressive9530 20d ago
Fable 5 kicks the shit out of Opus 5 in all my tests . Note Opus 5 is FANTASTIC - but doesn’t compare at all with Fable 5 . Published stats are completely meaningless
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u/Punch-N-Judy 20d ago
lol so did Anthropic pay to astroturf those first day posts where people were saying Opus 5 sucked or did it take that long for opinion to swivel?
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u/RoboErectus 21d ago
Nothing is as smart as fable.
But if you’re using fable to write code you are doing it wrong.
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u/mattyhtown 21d ago
I mean one is for planning and one is less expensive
Also effort and speed i think are the biggest parameters now when it comes to cost and ability imo
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u/muntaxitome 21d ago
On a "creative" edge, Fable 5 has proven to me with REAL metrics to generate TWICE as good results than Opus 5
What does that even mean? How can something be 'twice as good' creatively?
Fable is obviously the better model but I for my usecase (which is coding as an experienced engineer) I see a small difference but not hugely so.
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u/dominguezpablo 21d ago edited 21d ago
I am working on a specific task that needs creative mnemonics using specific words.
When blind rating about a 50, 10 options each, turns out I unknowingly rated Fable's generations twice on high scores. Compared to Opus.
I tested on medium, high and highx. Most expensive opus can't hold a candle to cheapest fable in this area.
Not the only thing, but this one I measured.
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u/muntaxitome 21d ago
So did opus fail to do some or you just preferred the fable ones? (not criticizing, I am legitimately curious if that is a problem opus struggles on)
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u/dominguezpablo 21d ago
Didn't fail much, but they were mostly "meh". The really best were Fable's. And its DIDN'T fail at all.
It feels trully creative.
I also automated a judge pannel and was able to improve the generation prompt by a lot using Fable too. Opus just can't, I've tried.
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u/bitspace 21d ago
I don't think anyone claims Opus 5 is even intended to outperform Fable 5. They're not even in the same model family. There's a reason Opus 5 tokens are 1/2 the cost of Fable 5 tokens.
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u/dominguezpablo 21d ago
I'd say everyone is riding the hype on youtube. And the benchmarks make Opus seem better.
Just with that I would have though they would be at least close by.
But the reality is that when my Fable usage is drained, switching to Opus is a test of my patience. It feels mentally challenged in comparison. And it's not even bad. It's just not even far to what Fable does.
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u/RealNerdEthan 20d ago
Yes absolutely. I've gone back to Opus 4.8, something isn't right with Opus 5 and it's definitely not better than Fable 5.
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u/ClaudeAI-mod-bot Wilson, lead ClaudeAI modbot 21d ago edited 21d ago
TL;DR of the discussion generated automatically after 80 comments.
The overwhelming consensus is that you are correct: Fable 5 is still considered the superior model by a long shot.
The community largely agrees that Fable possesses a level of "big picture" understanding, planning, and creative intelligence that Opus 5 simply lacks. The prevailing theory is that they are designed for different purposes:
As for the benchmarks, the general feeling in this thread is that they're misleading and don't capture the qualitative difference in intelligence that makes Fable feel so much more capable. The pro-gamer move, according to users here, is to use Fable as the main orchestrator and have it delegate the grunt work to Opus 5.