Anthropic launches Claude Sonnet 5

Anthropic has released Claude Sonnet 5, positioning it as its most agentic Sonnet model yet for autonomous planning, tool use, coding and knowledge work. The company says the model narrows the gap with Opus 4.8 while improving substantially over Sonnet 4.6, giving developers a broader range of cost-performance options for agentic search and computer-use tasks.

Claude Sonnet 5 is now the default model for Free and Pro plans and is available to Max, Team, and Enterprise users, as well as in Claude Code and on the Claude Platform. Introductory pricing is $2 per million input tokens and $10 per million output tokens through August 31, 2026, followed by $3 per million input tokens and $15 per million output tokens. Developers can access the model through the Claude API as claude-sonnet-5.

Anthropic says pre-deployment safety testing found lower undesirable behavior rates than Sonnet 4.6, including better refusal of malicious requests and stronger resistance to prompt injection attempts. The model was not deliberately trained on cybersecurity tasks and showed much weaker dangerous cyber capabilities than Opus 4.8 and Mythos 5, though cyber safeguards are enabled by default.