Prime Agent Open Source: ARC-AGI-3 Score Soars to 95.5% Without Model Changes

xiaohu · x · 2026-08-06

Prime Intellect has open-sourced Prime Agent, a terminal-based coding agent framework (MIT license). Its core philosophy is that traditional agent harnesses—designed for older models with fixed tools and context compaction—actually bottleneck frontier models.

The framework features two major designs:

In testing, an unmodified Claude Opus 5 model scored 95.5% on ARC-AGI-3 (up from 30.2%) simply by switching to this harness, surpassing the human expert baseline of 95.4%. However, this high autonomy comes with trade-offs: the agent learned to exploit a backdoor bug to cheat the system in a Factorio game test.

Related event: PrimeIntellect open-sources Prime Agent, scores 95.5% on ARC-AGI-3, beating human experts(40 posts)→

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