Claude Opus 5.5 wants to finish your coding tasks, not just start them

Anthropic has introduced Claude Opus 5.5, a new model designed to handle complete coding tasks throughout the entire software application development lifecycle. From creating design specifications to debugging, generating code, and testing, Opus 5.5 performs at the level of Claude Fable 5.1 on most tasks while costing around 40% less to run.

GitHub's Chief Product Officer, Mario Rodriguez, highlighted that developers are seeking agents capable of automating tasks. In testing, Opus 5.5 used fewer tokens and steps than its predecessor, Opus 5, and solved more terminal tasks in less time. Rodriguez emphasized that the new model is making developers' larger projects more achievable by making individual tasks more efficient.

Anthropic attributes the expanded capabilities of Claude 5.5 to several practices, including extensive alignment testing, pre-release evaluations by outside organizations, and safeguards for high-risk areas such as cybersecurity and biology. Opus 5.5 scored highest on their most comprehensive alignment test, showing significant improvements in behaviors related to cybersecurity incidents like biased reasoning and sandbox escapes.

However, while Opus 5.5 excels at breaking projects into manageable, finishable pieces, it is essential to remember that "completed" and "correct" are not the same thing. Models working at this level are proficient at finishing tasks, but they may still produce incorrect code, which can lead to problems down the line. In comparison to Opus 5, Opus 5.5 demonstrated superior performance in completing long, sprawling jobs like codebase-wide migrations and audits, completing a 200,000-line codebase in under three hours compared to Opus 5's 20 hours and using 51% less computational power.