Anthropic Introduces Claude Sonnet 5, Its Most Agentic Sonnet Model Yet
Anthropic launched Claude Sonnet 5, an agentic AI model that plans, uses tools, and operates autonomously at performance levels near Opus 4.8 for a lower price. The company said it improves on Sonnet 4.6 in reasoning, coding, and safety, with substantially weaker cybersecurity capabilities than Opus models.
Anthropic announced Claude Sonnet 5 on June 30, 2026, describing it as the most agentic Sonnet model released to date. The model can make plans, use tools such as browsers and terminals, and run autonomously at capability levels that previously required larger and more expensive models.
According to Anthropic, Sonnet 5 narrows the performance gap with Opus 4.8 while maintaining lower prices, and delivers substantial improvements over Sonnet 4.6 in agentic performance areas including reasoning, tool use, coding, and knowledge work.
Pre-deployment safety evaluations found Sonnet 5 showed an overall lower rate of undesirable behaviors than Sonnet 4.6, with better refusal of malicious requests and resistance to prompt injection attacks. However, automated behavioral audits showed somewhat higher rates of misaligned behavior compared to Opus 4.8 and Claude Mythos Preview. Anthropic noted the model has substantially poorer performance on potentially dangerous cybersecurity tasks than Opus models and launched it with cyber safeguards enabled by default.
Claude Sonnet 5 is available across all plans as the default model for Free and Pro users, and is accessible to Max, Team, and Enterprise users. It is also available in Claude Code and via the Claude API under the model name claude-sonnet-5. Introductory pricing on the Claude Platform is $2 per million input tokens and $10 per million output tokens through August 31, 2026, after which pricing will be $3 per million input tokens and $15 per million output tokens.
Source: Anthropic News
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