Claude Opus 5 Is Highly Capable, But Is No Mythos
Zvi (Don't Worry About the Vase) 1 month ago 10 ● 5 sources
Anthropic released Claude Opus 5, positioning it as a cheaper alternative to their flagship Fable 5 model at half the API token cost while delivering comparable performance on most real-world tasks. Opus 5 achieves state-of-the-art scores on benchmarks like Frontier-Bench and GDPval-AA, and is notably the most resistant to prompt injection attacks of any Claude model to date. However, the model struggles with high-level autonomous reasoning compared to Fable, has polarizing personality traits that many users find off-putting, and ultimately does not expand what's possible—it mainly offers a cost-effective option for specific use cases like subagent work and bounded tasks.
