Anthropic released Claude Sonnet 5, positioning it as the most agentic version of its mid-tier AI model. The new model replaces Sonnet 4.6 and can autonomously plan, browse, and execute tasks that previously required larger, more expensive models. It bridges performance gaps with the premium Opus 4.8 while maintaining cost advantages.

Introductory pricing runs through August 31, 2026, offering $2 per million input tokens and $10 per million output tokens. After that period, costs increase to $3 and $15 respectively. Anthropic increased rate limits across Chat, Cowork, and Claude Code to handle higher token usage from more complex agentic workflows.

Sonnet 5 becomes the default for both Free and Pro Claude users. The company also offers Mythos 5 with fewer guardrails for security researchers, while Fable 5 faces US government restrictions. Claude Opus 4.8 arrived in late May, with Mythos 5 partially restored to select customers.

This represents Anthropic's push to make advanced agentic capabilities more accessible through pricing and performance improvements, challenging competitors who still rely on expensive model tiers for autonomous task execution.