Introducing Claude Opus 5

Summary

Claude Opus 5 is available as a new model positioned near the frontier intelligence of Claude Fable 5, at half its price, while remaining behind Mythos 5 on cybersecurity tasks. Reported results show state-of-the-art performance on coding and knowledge-work evaluations, including Frontier-Bench, alongside strong results on ARC-AGI 3, Zapier AutomationBench, and OSWorld 2.0. The model uses configurable effort settings to trade intelligence for token use, speed, and cost, and is described as stronger at verifying work, iterating, and handling long agentic tasks. It costs $5 per million input tokens and $25 per million output tokens, with Fast mode running about 2.5 times faster at twice the base price. Safeguards allow vulnerability finding while blocking binary-based scanning, penetration testing, and exploit generation, with flagged requests able to fall back to Opus 4.8.

Takeaways

1. 1

   Effort settings let customers optimize for intelligence or conserve tokens for faster, cheaper results; on CursorBench 3.2 at maximum effort, Opus 5 came within 0.5% of Fable 5’s peak score at half the cost per task.

2. 2

   On life-sciences evaluations, Opus 5 outperformed Opus 4.8 across the set, including gains of 10.2 percentage points on spectroscopy-based organic chemistry tasks and 7.7 points on protein-variation tasks.

3. 3

   Developers can use claude-opus-5 through the Claude API; beta updates add mid-conversation tool changes without invalidating the prompt cache and automatic fallback routing for classifier-flagged requests.