Anthropic Releases Claude Sonnet 4.6 With High-Effort Reasoning
- •Claude Sonnet 4.6 secures second place on Intelligence Index, trailing only Opus 4.6.
- •Model achieves top scores in GDPval-AA and TerminalBench, outperforming competitors in agentic tasks.
- •New adaptive thinking mode enables better performance but increases output token usage by 3x.
Anthropic has unveiled Claude Sonnet 4.6, a significant update that positions the model as a powerhouse for complex, multi-step operations (agentic tasks). In recent evaluations, the model achieved an Intelligence Index score of 51, marking an 8-point jump from its predecessor and placing it nearly on par with the flagship Opus 4.6. This narrow gap suggests that for most high-level applications, the distinction between the "Pro" and "Premium" tiers is blurring.
One of the most striking features is the introduction of "adaptive thinking," which replaces the previous extended thinking mode. This allows the model to adjust its internal reasoning process based on a user-defined effort level—ranging from low to max. While this significantly boosts accuracy in coding and real-world task simulations, it comes with a trade-off: a massive increase in output tokens. In max effort mode, Sonnet 4.6 generated three times more tokens than the previous version, leading to higher operational costs despite identical per-token pricing.
For developers focused on building AI agents that use terminal commands or handle professional workflows, Sonnet 4.6 is currently the top-performing model on the market. It now supports a massive 1-million-token context window in beta, allowing it to "remember" and process vast amounts of documentation or code simultaneously. This combination of reasoning depth and expanded memory makes it a formidable tool for autonomous software engineering and complex data analysis.