Anthropic Adds Claude Sonnet 5.5, Sharpening the Choice Between Speed, Cost and Frontier Reasoning

Anthropic has added Claude Sonnet 5.5 to its Claude 5.5 family, six days after introducing Claude Opus 5.5, giving users a faster and cheaper default option while keeping Opus positioned for harder long-horizon work. The release makes Claude’s model picker more capable but also more complex, as developers now have to weigh effort settings, context limits, safeguards and task shape before choosing a model.