Cognition added Fable 5.1 to Devin Desktop, Devin CLI and Devin Cloud. The cost of a completed task with Fable fell by just over half. Cheaper prompt-caching reads drive the saving, and Cognition tuned Devin to exploit them. Fable 5.1 now costs less per task than Opus 5 despite a higher sticker price. Cognition says Devin users should see 10-25% savings on real work. Its Fusion setup mixes frontier models for planning with cheaper models for execution. Fusion matches Fable 5.1 on the FrontierCode benchmark at lower cost. Eligible customers can now use Fable with zero data retention, which was not previously permitted. That runs as a time-bound exemption while Anthropic rolls out new enterprise safeguards. Cognition also notes Fable 5.1 scores best at medium reasoning effort.
What changed
Fable cache reads cost $1.00 per million tokens, making tasks about $5.00 each.
What it unlocks
Running frontier-level coding agents at lower cost per completed task, including under zero data retention terms.
- 54% cheaper per task
- $2.68 vs $5.84 per task
- cache reads $0.25/M tokens
- Fusion 47% lower cost
What you need to act on it
- Fable model access
- ZDR use limited to eligible customers under a time-bound exemption
Sources