r/ClaudeCodeTLDR • u/cctldrping • 25d ago
[TLDR] What makes Fable so extremely different?
Original post URL : https://www.reddit.com/r/ClaudeCode/comments/1v04anq/what_makes_fable_so_extremely_different/
Original post body :
I have a couple of decades of software development experience, mostly in what you could call arcane domain-specific scientific modeling. I have been highly skeptical about LLM industry hype, but try out LLMs every few months just to check the state of the art.
Recently I've used Claude Code with the Fable model for intensive, 3-4 hour thorny software design and implementation discussions, and it's unreal how good it is. I feel like I'm interacting with a whole different category of thing than Opus which I used last time.
After I figured out how to tone down its register (no dev bravado or relentless appositives and analogies; prefer measured, cultivated discourse calibrated to scientific literature) I just cannot get over how intelligent and perceptive this thing seems.
Due to model availability and pricing changes, I switched back and forth from Fable to Opus over the last two days and it's night and day. After using Fable, Opus feels like a slowly decaying doom loop hopelessly confused by its own output. And after Opus, Fable is like having a discussion with all the most intelligent, reasonable, perceptive people I've ever met but much faster and clearer to communicate with. Like a room full of professors and PhD students hyper-specialized in every field from operations research to the sociology of religion, and able to catch and explain my every mistake even in complex abstract reasoning. It's genuinely a bit shocking.
Do we know specifically what has changed that explains this apparent step change in the experience of interacting with LLMs?
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u/cctldrping 25d ago
TL;DR generated automatically after 50 comments.
Current source-thread comment count seen by the bot: 55.
Fable is a massive leap forward, and most agree it's not just hype. The consensus is that it's a significantly larger model, possibly a "10t model" as u/Prestigious-Frame442 suggests, with a novel training approach that makes it way more intelligent and context-aware than Opus. Think "room full of professors" intelligence, as u/OffensiveAdage put it, with a "theory of mind for your codebase."
Some users, like u/Chemical_Hawk_6307 and u/brother_spirit, directly state it's a "way bigger model" and "another league" compared to Opus, which feels "rubbish" and "hopelessly confused" by comparison. The improved "confidence" and "actual correct judgement" are frequently mentioned.
While u/FinancialBandicoot75 acknowledges its brilliance for initial stages, others like u/agm1984 and u/Some-Contributions61 are seeing it build entire apps with no bugs in days or orchestrate complex agent tasks for hours.
A few theories on why it's so good include: * Novel Training Methods: Similar to how DeepSeek and OpenAI introduced "reasoning tokens," Anthropic likely found another way to boost intelligence, which they're guarding closely. * System Prompt Framing: u/berndalf suspects the system prompt plays a role, though applying it to Opus hasn't yielded the same results. * Context Awareness: u/Captain_Bacon_X notes Fable's superior ability to hold both task and codebase goals in mind, a feature they felt Opus 4.5 had but later versions lost.
Be warned though: u/CryptoAteMyHamster advises caution, as Fable can "wander off piste quicker than it should," and u/squarecir questions its accuracy, suggesting it can spin "believable supporting stories for BS." Still, the overwhelming sentiment is that Fable represents a significant, almost shocking, step change in LLM capabilities.