Anthropic launches Claude Sonnet 5 with cheaper agentic AI capabilities

Anthropic has unveiled Claude Sonnet 5, its latest AI model focused on delivering stronger agentic AI capabilities at a lower cost. The company says the model is designed to handle autonomous tasks that, until recently, required significantly more expensive AI models.

While Sonnet 5 is not as capable as Anthropic's flagship Claude Fable 5 or Mythos 5 models, it brings several improvements over Sonnet 4.6 and narrows the performance gap with Opus 4.8. Anthropic says the model has been optimised to deliver near-Opus 4.8 performance while offering a more affordable pricing structure.

Starting Tuesday, Claude Sonnet 5 will become the default model for both Free and Pro users and will be available across all Claude subscription tiers.

According to Anthropic, Sonnet 5 improves on Sonnet 4.6—released in February—across several agentic AI capabilities, including reasoning, tool use, software engineering and knowledge work.

Benchmark performance

In benchmark testing, Sonnet 5 scored 63.2% on an agentic coding benchmark, improving on Sonnet 4.6's 58.1% while trailing Opus 4.8's 69.2%. However, on a separate knowledge work benchmark, Sonnet 5 outperformed Opus 4.8, highlighting stronger performance in reasoning, research and complex knowledge-based tasks.

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According to early testers, Sonnet 5 is also better at completing complex, multi-step tasks that previously required manual intervention. The model was found to verify its own outputs more consistently, enabling it to execute end-to-end workflows with greater reliability.

Safety improvements

Anthropic says Sonnet 5 also delivers improved safety compared with its predecessor. The model demonstrates lower rates of hallucinations, deception and other undesirable behaviours, while showing stronger resistance to malicious prompts and prompt injection attacks. It is also better at rejecting unsafe requests, making it more suitable for agentic AI applications.

Pricing

At launch, Sonnet 5 is priced at $2 per million input tokens and $10 per million output tokens through August 31. Beginning September 1, the input token price will increase to $3 per million, while the output token price will remain unchanged at $10 per million.

Anthropic says Sonnet 5 is priced below Opus 4.8, OpenAI's GPT-5.5 and Google's Gemini 3.1 Pro, although it remains more expensive than Gemini 3.5 Flash.