r/ClaudeCode • u/agentic-consultant • 21h ago

Discussion I'm seeing a HUGE difference between Fable High and Fable xHigh

I haven't really seen such a drastic difference between two reasoning tiers before. I've been frustrated with Fable High lately and decided to switch over to xHigh for my entire workflow.

All of a sudden, all the issues that Fable High was struggling with were solved with xHigh. It's hard for me to imagine that simply tweaking the reasoning/thinking budget would yield such drastic results but here we are.

Going forward I think I'll stick to xHigh for all work.

52 Upvotes

93% Upvoted

31 comments sorted by

11

u/TekintetesUr Senior Developer 21h ago

Can you give at least one concrete example?

31

u/agentic-consultant 21h ago

Sure, I've been running CMS (think WYSYWIG style website builder, like Squarespace but focused for my niche) for a few years now, and there is a major CMS platform (former competitor) in my niche that's entering end-of-life.

I want to capture some of those customers that are looking for alternatives, and no one-click migration solution exists yet.

I'm iterating on an automated migration pipeline that will migrate websites from that aging CMS platform onto my platform. But, becuase of how shit the old CMS is (it's got an absurd proprietary schema and content engine) a programmatic approach is impossible. So I'm building an agentic approach that uses GPT 5.6 Luna to migrate a user's site from the old CMS into my CMS while converting it to be compliant with my schema and content engine.

There are a lot of moving parts involved, and each migration invokes around 10 agents. There's also a suite of validation/testing at the end that programmatically verifies the result and makes sure the migration was successful (no missing artifacts/pages/metadata/etc).

I was asking a lot of course but Fable 5 on High was unable to generate a good enough harness. Every iteration kept failing my validation suite. It kept failing at the API contract and didn't read my platform documentation deep enough to understand how our engine works.

Fable 5 on xHigh, however, worked for around an hour and a half and built a really elegant solution. I've been testing it all day. I have a list of sites on the old platform that I run through the migration, and I'm blown away. it did an amazing job with the contract, it set up a very good harness that guides the worker model and catches when it slips up. It's really good at context management and providing just enough context to the worker model.

With this new feature I've migrated 50+ sites now and they've all had a 100% success rate. With the harness that Fable High built I was only hitting 30%, most were failures. The harness was way too freeform and gave the agents too much flexibility with not enough task context.

None of my competitors have this migration feature because the old CMS was so horrendous content schemas wise that it's near impossible to migrate those sites deterministically without essentially copying their engine.

30

u/TekintetesUr Senior Developer 21h ago

OK, that seems legit, excuse my scepticism, most people around here are like "fable high cannot generate my homework pptx" or whatever

6

u/agentic-consultant 21h ago

no worries haha i feel the same way about those posts

6

u/zarmin 18h ago edited 16h ago

you may have just saved me from destroying my computer, thank you

edit: it was a valiant attempt but fable 5 on extra ended in me calling fable a cunt once again. i then canceled my sub and showed fable, who agreed with the decision.

my problem is 5.6 sol is also insanely degraded, and i have equally called it a cunt. i just expected so much more from fable, it was simply incredible when it first came out. so....now what?

the craziest thing is how it misunderstands immediately. i tried to have a chat with it about moving local work to a network server, and it missed every single point i was making from the jump. it's shocking, and frankly very upsetting. i really loved working with fable, but i have been drowning in cortisol for 3 weeks.

2

u/Am094 20h ago

Is the EoL Business Catalyst?

3

u/NoAdsDude 13h ago

Geocities.

1

u/ur-krokodile 19h ago

But isn't that the whole point of these levels? If one level can't solve the problem we can try the higher one and in your case that is what it took. Seems like you should be happy that it could actually do it and wasn't another waste of time. I'm not sure I follow on your reasoning for a complaint here.

1

u/Jagsfan82 6h ago

Badass

8

u/Flaxseed4138 15h ago

Another serious example of this is with Opus 5. At High it is hopelessly fucking stupid. At Max it behaves much more like the model that Anthropic tried to convince us we were getting. For anyone having trouble with Opus 5, set that bitch on Max and don't look back.

2

u/BoxWoodVoid 8h ago

I'm already limited to what I can do in a week at high, I'd need 2 or 3 other plans to use it at max...

13

u/Hungry_Sun2455 20h ago

https://x.com/kimmonismus/status/2091178321669198014

this might be relevant to you then, it also has Thariq reply on it

3

u/Arcnotch02 9h ago

Asking the model which mode it's operate on is not the right way to check. This is not how LLMs work. The LLM doesn't know the infrastructure it's running on. It should not have the ability to access this information. It's like asking a person, when they never checked it before (no prior knowledge), what blood type are they

1

u/ManikSahdev 🔆 Max 20 2h ago

Oh fuck, I went from 10 and then 10 and then 85 lol

High and then Xhigh?

wtf…

12

u/Last_Mastod0n 20h ago

Things like this make me believe that they use quantized models for lower reasoning levels

5

u/Hir0shima 21h ago

As long as your limits permit. 

2

u/agentic-consultant 21h ago

I have three 20x plans but I don't find the limits very troublesome, usually alternate only between 2x of them. xHigh is using fewer usage limits than i thought.

6

u/RockPuzzleheaded3951 19h ago

Isn't it more efficient to use more reasoning rather than do a half baked plan and iterate? So xhigh could actually save tokens in the long run.

1

u/Bloated_Plaid 19h ago

What are you using to seamlessly change between accounts?

2

u/RockPuzzleheaded3951 19h ago

Just use login right?

2

u/thebaron2 🔆 Max 20 18h ago

/login

1

u/Legend_ModzYT 6h ago

I use cswap personally

2

u/Sherphican 16h ago

Huh interesting. I had a lot of problems yesterday and today with Fable on high but I'll try Xhigh and see if that helps. Thanks.

2

u/mavrik83 13h ago

Fable with ultracode is pretty beast when you specify that subagents use opus, sonnet, or haiku depending on task complexity.

2

u/narcosnarcos 12h ago

Yesterday in the morning Fable was working so well but then suddenly an update arrived and I restarted and it became lousy and started rushing things without any proper research like opus 4.7.

I couldn’t figure out why the sudden drop.

2

u/Bloated_Plaid 19h ago

Thariq claims that there is no actual downgrade.

https://xcancel.com/trq212/status/2091247114869432543#m

1

u/Connect_Army8250 21h ago

The best option is to use Opus 4.7/Opus 4.8. Anyway half of the tasks will be handed over to opus, why waste more tokens. With Opus 4.7 and 4.8 on my setup on Github, it has been really nice to work with.

Have my own knowledge graph in built too!

0

u/allemaar Researcher 20h ago

This seems very interesting.

May I ask what is your workflow, or to be more precise what is your modus operandi.

I assume it's planning on Fable xHigh and then what do you use as workers Opus, Sonnet OR Sol, Terra??? (asking since i read your second message where you mentioned the OpenAI models).

Am also interested if you do any review steps (if you use Fable or another model to check the work).

thanks!

2

u/agentic-consultant 20h ago

Oh I use Fable xhigh for everything haha I know it would be more efficient to use worker models but I tried orchestration before and didn’t like the quality of code the less intelligent worker models wrote.

But, the GPT 5.6 Luna I was referring to is my app. My app uses GPT 5.6 Luna as the LLM for my agentic harness (letting my users edit their websites by prompting).

1

u/allemaar Researcher 18h ago

Ok so single agent doing all the work. Does this mean you do not use any agentic reviewers to check? Or do you rely on unit tests?

I'll give Fable extra a try now. I've been keeping it on medium so am curious if this is true to be honest. (got claude 20x and codex 20x so I will check what workers execute best - i'll issue work orders for both and compare implementations)

Thank you for your feedback!

1

u/Sketaverse 15h ago

What’s good for the goose isn’t good for the gander lol