Anthropic's Opus 5 is about token efficiency, not a capability leap

# Anthropic's Opus 5 is about token efficiency, not a capability leap Source: [https://arstechnica.com/ai/2026/07/anthropics-opus-5-is-about-token-efficiency-not-a-capability-leap/](https://arstechnica.com/ai/2026/07/anthropics-opus-5-is-about-token-efficiency-not-a-capability-leap/) Today, Anthropic[rolled out Opus 5](https://www.anthropic.com/news/claude-opus-5), the newest update for the model that has recently become a popular choice for coding and other software development tasks, among other things\. While this is a noteworthy bump for Opus, it doesn’t seem to be an Opus 4\.5\-level breakthrough in agentic coding performance\. A chart \(made by Anthropic\) with various benchmarks like Frontier\-Bench and DeepSWE shows Opus 5 performing at about the same level or slightly ahead of the much\-ballyhooed capabilities of Anthropic’s Fable model for coding tasks\. It ostensibly beats Opus 4\.8 and OpenAI’s competing GPT\-5\.6\-Sol in just about every kind of task\. The various benchmarks show an iterative increase in performance, but not a radical leap, while the main pitch is that it’s a model that offers something just shy of Fable at approximately half the cost\. It’s also worth mentioning that Anthropic specifically avoided giving Opus 5 cutting\-edge training on cybersecurity tasks, so it lags way behind Fable and Mythos in that regard\. Anthropic claims it is relatively good at finding cybersecurity vulnerabilities, but because of decisions made in training the model, it is “substantially behind Mythos 5 on the*exploitation*of those vulnerabilities\.” As such, Opus 5 doesn’t have all of the same controversial protections that Fable had, such as the policy of keeping data for review for 30 days in case of an incident\.