Cognition Says Pairing Fable with Its "Fusion" Sidekick Setup Beats Opus on Cost and Score
Cognition, maker of the autonomous AI software engineer Devin, has published results showing that pairing its multi-agent “Fusion” configuration with Anthropic’s Fable 5 costs less and scores higher than running Opus 4.8 alone. The analysis is based on 3,000 evaluation sessions run on FrontierCode 1.1.
Details
- Score and cost comparison: “Fable + Fusion” (a sidekick setup) costs $1.86 per run with a score of 60.7, versus “Opus + Fusion” at $2.04 per run with a score of 54.6 — Fable comes out both cheaper and higher-scoring
- Versus plain Fable: Using Fable in the sidekick configuration cuts cost by 54% versus running Fable alone, while maintaining performance
- Behavioral difference: Cognition describes it as “Opus behaves like a micromanager with an intern; Fable is a manager with a capable engineer” — Fable delegates early with clear constraints, while Opus tends to delegate only after expensive exploratory work
- Scale of testing: The analysis draws on 3,000 evaluation sessions run on the FrontierCode 1.1 benchmark
How to try it
- This post is a technical analysis of model-routing strategy inside Devin, not a standalone new feature or product
- Full methodology and data are published on Cognition’s official blog