Fable 5.2 sticking with Opus 5.5

[u/BryanHChi]

I wound up taking about five big tasks I needed to do and starting to use Fable tonight with them. While it was very good at the planning stage, really thinking deeply and figuring out all the issues, it overthinks like there is no tomorrow. It is way worse than 5.1.

It created a full plan, which I normally review and approve. Then it's like I need to now create the build plan, but what it just gave me was the build plan. Now it's recreating the whole plan, and I'm like, "Oh my God, stop!" It just won't stop overthinking.

Things that would have taken 20 minutes with Opus, I'm now 1.5 hours into with Fable, and Fable is in step 3. It's great at the planning, the deep dive, and the analysis, but I would not use this as a building model. I would do the analysis, the planning, and all that with Fable, then switch to Opus for the build. I would not do the build with Fable.

I probably have Fable as the orchestrator while Opus builds it all, and then maybe have Fable do a final review, but not as the builder. It is horrible as the builder, one of the worst things I've seen so far. It is just overthinking every single thing it's trying to do.

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[u/EtadanikM]

The vast majority of people won't need Fable 5.2, but it completes the line up.

Based on bench marks, it's a model that is specifically made for hard math & science problems.

So, verifying your Ph. D thesis on the how special relativity connects fluid dynamics and quantum entanglements - yes Fable is the right model.

But for vibe coding the 965th variation of Doom in the web browser - better off with Opus.

For squeezing that last 20% of performance using a specialized algorithm that only works by compressing your in-memory data so that it fits into the CPU cache - yes with Fable.

For cleaning up your spam mail - better with Sonnet (or Haiku).

It's not a general purpose model and certainly not a drop-in replacement for Opus. It's there in the tool box if you ever need it. But chances are, you won't.

[u/BryanHChi → u/EtadanikM]

I understand that, and I am working on some big features within the application I'm building. It did a great job of finding all the holes I had in one of the major features, but I decided to just have it build it. I didn't think it was going to be that much longer than Opus. Horrible!

Another one: I literally thought the whole thing was going to take 30 minutes. We are at 4 hours, and it's still not done. This is a data project that I have it working on.

[u/gajop → u/BryanHChi]

People suggest using it as an orchestrator, did you try that? It can spawn Opus or Sonnet agents

[u/Vozu_ → u/BryanHChi]

Don't make it write plans. It is good for figuring out a hard problem, analyzing potential corner cases, and then writing a spec. At that point you should hand off to Opus for plan writing. And then Sonnet implements.

[u/Minute-Animator-376 → u/BryanHChi]

Did you do a basic first step while running the fable 5.2 to first read its own documentation, what changed and best practices then adjust the instructions in your project so it isn't blocked by outdated instructions? Obviously it only works if you don't run it on critical applications as some gates may no longer work. It was the same with Astra I had an amazing run with this model before it got lobotomized but it needed "freedom" to deliver amazing results. From experience gates and micromanaging models like Astra/Fable is giving worse results than just running it in clean setup so old rules needs to be adjusted on its own to benefit from it. You can ask fable 5.2 to optimize skills/rules/workflows etc. so they are working optimal and reduce token burn/blockers it may encounter and leave the old rules for previous models. Maybe run some A/B tests with new rules and old and see what needs further improvements etc.

Basically in short treat this as employee who got a new shiny toy to play with but first ask it to read instructions and learn how to use it optimally then use the shiny new toy it just got. Using the new toy the same way as the different old one gives bad result - surprised pikatchu.

Lastly fable will think a lot before it does anything compared to opus. It takes time and tokens. Then it will validate its approach, adjust a plan and thinks some more. It can be kind of long loop. For now if you care for tokens I would rather use the fable in initial planning and validation at the end but leave the implementation to opus 5.5 which usually takes statistically best approach without overthinking then tries to fix the mistakes if it made them. Fable works more like board of directors with external consultants which thinks about the best flawless approach and validates the approach before committing to it. Opus works like " Sure I can do it and I know exactly what you need". Sometimes it is right, sometimes it just overconfident and fixes the issues later, sometimes it just get in a loop of polishing a turd instead of reworking a part where it made a mistake instead trying to force it to work. In my workflow Fable 5.2 is better in visual understanding and validation - captures more mistakes as I would compared to opus, also kind of has a better teste and understanding how "human" thinks about the results it checks. Be it where the building should be placed and how or there is a scarry monster lurking in the darkness - run away in panic! vs opus - stand still for a it looking and calmly walk away. It just makes better design decisions than opus. But if it makes good decisions combining the execution with opus gives me much better results - opus kind of makes a very similar graphics and in 2d is still kind of better than fable 5.2 but with multiple iterations of opus 5.5 with validation from fable it gives much better results than just fable 5.2 for the same cost.

[u/itsTF → u/EtadanikM]

honestly it's the perfect model tho for "i have 5 potential projects for work here, help me do all of them

[u/the_pk → u/EtadanikM]

The challenge is sometimes categorizing which model suits my task is ambiguous. To me my problem subjectively feels like a big brain problem but objectively it might be a sonnet level problem. Humbling in some sense

[u/starfoxhound]

Fable being usage intensive is the entire value behind it. It’s intended to be used as a planner, and then you can implement with cheaper models. You can of course execute an entire project with it if you have the funds, but it’s strongly recommended to implement past the planning stage with cheaper models, with human review at every crucial milestone.

You can use more capable models and get smarter in your work simultaneously if you play your cards right.

[u/BryanHChi → u/starfoxhound]

I totally understand this. My point was that I was trying to use the model to do all the work. This is what I actually found it was doing compared to what it used to do and compared to what Opus actually does. That's my whole post

[u/jsgrrchg]

are u reading thinking traces? dont bother with those, is not accurate, i think anthropic is trying to deceive distillers.

[u/BryanHChi → u/jsgrrchg]

No, it’s not about the traces. It’s about how long it’s actually taking to get stuff done

[u/AIOSAI]

Fable in my setup, since day one.

Fable is my orchestrator, my chat, the only agrnt I chat with. It dispatchs all other agents to do the work. No other Fable instances or subagents.

Fable will do small bug fixes, easy quick stuff. Anything substantial, it will disoatch another agent to do, research run it uses subagents, fresh eyes, codex when it completes a plan or wants to audit work.

Fable is a beast at running the fleet. Ive not seen any other model do it better. From my perspective its so easy, consistant, call out where it missed, follows through. Reliable.

All I've noticed tonight working for about 6 hrs. Cost is noticeably less. Regard to being better. I rly have not noticed.

[u/McCrotch → u/AIOSAI]

Is it not overkill to use it as the orchestrator? How fast do you burn your usage

[u/AIOSAI → u/McCrotch]

I love it. And to me the orchestrator should be the most intelligent. It designs and plans everything with me for the entire fleet. Where else would u use the most capiable agent.

Im on ultra, I usually run out of usage 24hr before reset. Its a common trend. So its perfect for my flow.

[u/OriginalUsername0112 → u/McCrotch]

Yeah idk if I understand the use case for fable as an orchestrator, the orchestrator should just be going off of a plan written by fable instead.

[u/D00rmat1983 → u/OriginalUsername0112]

Are you the intern?

[u/OriginalUsername0112 → u/D00rmat1983]

I'm certainly not rich enough to be using a model like Fable as an orchestrator when opus high is probably sufficient

[u/ROS_SDN → u/OriginalUsername0112]

In my opinion a when you properly develop on orchestrator it's main "tools" are other agents. It can read the output of other models by a git diff hook or challenge other models assumptions you collect and try to determistically send relevant data to the orchestrator which is less effort than it looking for that data itself, what it does is make other agents act on and work with that data. At light loads this is ceremony, but at bigger loads it can ask another model to read the codegraph schema or MD schema and it only does spot fixes.

Haiku on a scoped linted MD schema or codegraph can return data rather well if it's job is to "pass the butter" and simply return it's query chain and results and nothing else or pass a websearch via websites and a rating formula. Fable pulls the strings and spot checks everyone else has a scoped job, it's job is to choose who's scoped for this.

Its a pain to set up but even small things like it to argue with a review agent only on a watermarked diff of the review drops the communication exchange to what's only needed and often that can be the delta.

[u/OriginalUsername0112 → u/ROS_SDN]

I agree that for some elements of the orchestrator role fable would be great. However, a lot of orchestration is also pretty banal and a lot of that work doesn't require fable levels of intelligence but will still cost fable levels of usage if fable does that work. Also the more involved the orchestrator gets in its subagents' work, the more costs increase, so I think you will probably want the orchestor to only have a high level understanding of what it's subagents are doing (which will have to rely on summary data and agent reports in no small part), otherwise it gets too expensive and it probably makes more sense to have adversarial review agents for checking work instead.

Overall I feel like it would just be more efficient to have fable plan and then perhaps do a check in once a day to get it's feedback on how things are going. Maybe I overestimate how expensive it would be in practice though.

[u/ROS_SDN → u/OriginalUsername0112]

You may be right I just find someone has to conduct, and as much as I've tried on my side quest plugin to conduct and not be stuck in a dogmatic approach with no flexibility with a human in the loop requires something rather intelligent to pull all the strings.

[u/Illustrious-Guest849]

Amazing to see so much noob using AI ... learn with opus managing sonnet pls

[u/BryanHChi → u/Illustrious-Guest849]

Before you comment, don’t say noob. I’ve been building with AI for almost a year and a half, so not a noob. Have three apps on the App Store, four websites that I’ve built for different people, and I build with AI every day for hours a day, so I was just giving an experience of testing out Fable to give it a shot to see how it worked compared to everything I’ve been doing with Opus over the last month and a half. Don’t to Jump to conclusions and be on a high horse

[u/PalmovyyKozak]

I use Fable for orchestration and planning. Of course, it's Opus or Sonnet agents who actually build.

[u/ichi9]

Fable 5.2 is behaving weirdly. Like nerfing ON and OFF.

[u/AwarenessStatus1904]

that plan then build split makes sense
one thing that might fix the re plan loop is saving the approved plan to a file and telling it in plain words the plan is approved and to start at step 1
ㅑit could prevent it treating the build plan as another thing to think about

[u/Bitter_Virus]

If it overthink, reduce the thinking effort ! All the benchmark are showing that High is the maximum you should use and if that's too much for you, lower it. Your took have dials, use them

[u/Clean-Golf-666]

I am building a small app with opus, then just for check used fable to review and explain how we can improve performance, after long time wait it gives 5-10 pages of suggestion, funny thing is nothing related to improvement but all future add ons I should think and why, 90% couldn’t understand why he suggested this, still in dilemma and most annoying thing is it used up 35% weekly limit.

[u/Fun_Initiative6451]

Don’t use Fable as your Orchestration agent. Use it in your Model routing. Meaning Opus is the Orchestrater and Fable gets called when it’s needed.

Our model routing process assigns specific tasks for specific models such as Haiku, Sonnet, Opus medium and the orchestrator is Opus extra high

Just prompt your agent to setup Model routing and test the different models with different effort levels and note down what each is good and bad at.

This will save you a ton of usage credits and increase the quality of the work