Updated July 1, 2026. Fable 5 is available again after the June export-control suspension — at 50% of weekly limits on Pro/Max/Team through July 7, usage credits after. Opus 4.8 was unaffected throughout. Latest news →
FableGuide › Fable 5 vs Opus 4.8
The numbers
| Fable 5 | Opus 4.8 | |
|---|---|---|
| Model ID | claude-fable-5 | claude-opus-4-8 |
| Price (in/out, per MTok) | $10 / $50 | $5 / $25 |
| Context window | 1M tokens | 1M tokens |
| Max output | 128K | 128K |
| Thinking | Adaptive only; disabled 400s — omit instead | Adaptive only; explicit disabled accepted |
| Min cacheable prefix | 2,048 tokens | 4,096 tokens |
Where Fable earns the 2×
- Long-horizon autonomy. The headline gap. Stripe's 50M-line one-day migration and the FrontierCode top score are Fable results; with file memory, Fable improved 3× more than Opus 4.8 did on the same setup. Receipts on the evidence wall.
- Token efficiency. Fable is more token-efficient than past Claude models — Notation Capital measured a third of the reasoning tokens on physics research — so effective cost per completed task is closer than the sticker suggests.
- Vision. State-of-the-art; the Pokémon-FireRed-on-vision-alone result has no Opus equivalent.
Where Opus 4.8 stays the right call
- Daily-driver work. Opus 4.8 remains excellent for ordinary coding, writing, and analysis — at half the price. If a task wasn't straining Opus, Fable mostly buys you margin you don't need.
- High-volume production routes where cost dominates and tasks are well-specified.
- It's also Fable's own fallback — when Fable's safeguard classifiers trip, Opus 4.8 handles the response. Since the July 1 return, Fable's new safety classifier makes this more visible: its deliberately expanded margin false-positives on some routine coding and debugging, and in some flows the task is handed to Opus 4.8 with a notification. Anthropic itself routes to Opus when Fable steps aside — sometimes whether you asked or not.
Migration cost: one line
Same API surface. Swap the model string; the only new 400 is explicit thinking: {"type": "disabled"} — omit the field instead. Full checklist in Recipe 01.
The routing rule
| Work | Send to |
|---|---|
| Overnight agentic runs, large migrations, hardest debugging | Fable 5 |
| Tasks where one wrong answer costs more than the tokens | Fable 5 |
| Daily coding, writing, review, analysis | Opus 4.8 |
| High-volume pipelines with tight budgets | Opus 4.8 (or Sonnet) |
Updated July 1, 2026: the verdict holds, with one gate added. Fable 5 is available again — but subscription access runs at half of weekly limits through July 7, then moves to usage credits, so Opus 4.8 remains the daily default for subscription users. And note the new classifier occasionally makes the routing decision for you, handing routine coding to Opus with a notification even when you picked Fable.
Moral: don't ask which model is better — ask which tasks were failing. Those are Fable's.