Anthropic touts new Claude Sonnet 5 model range, offering performance ‘close to that of Opus 4.8, but at lower prices’ – here’s what users can expect
Anthropic has launched Claude Sonnet 5 in a move the company said offers users more powerful agentic capabilities.
The new option is the “most agentic Sonnet model yet”, according to Anthropic, capable of building workflow plans for users, accessing browsers and terminals, and operating autonomously for longer periods.
Cost and performance are key talking points here for Anthropic, with the company noting that Sonnet 5 “narrows the gap” with its flagship Opus range in terms of efficiency.
“Claude Sonnet 3.5, 3.6, and 3.7 were the first models that showed impressive skills in coding and tool use. More recently, though, the clearest gains in agentic capabilities have been in our Opus-class models,” the company said in a blog post.
“Its performance is close to that of Opus 4.8, but at lower prices,” Anthropic added. “It’s a substantial improvement over its predecessor, Sonnet 4.6, on important aspects of agentic performance like reasoning, tool use, coding, and knowledge work.”
SWE-bench Pro results show that show that Sonnet 5 recorded a 63.2% score on agentic coding capabilities. That marks a solid increase compared to Sonnet 4.6, which came in at 58.1%.
The model still lags behind Opus 4.8 (69.2%), but clear gains are being made on this front.
Anthropic eyes cost improvements with Claude Sonnet 5
With concerns mounting over token consumption, Anthropic is keen to emphasize that Sonnet is a far more cost-efficient model.
Performance of the model at “different effort levels” – or the intensity and timeframe of tasks – on BrowseComp shows a “strict improvement” over Sonnet 4.6.
Compared to Opus 4.8, meanwhile, Sonnet covers a “much wider range of cost-performance options”.
“It provides substantially improved cost efficiency at medium effort,” the company explained. “Its higher-effort performance can match Opus 4.8 on some tasks.
Users will also be able to adjust effort levels to help them “find the right balance of cost and performance” with both Sonnet 5 and Opus 4.8.
Sonnet 5 safety improvements
On the safety front, Anthropic noted there has been an “overall improvement” with Sonnet 5, which is far more likely to refuse “malicious requests” than 4.8 and is capable of resisting hijack attempts, such as prompt injection.
“The model shows lower rates of hallucination and sycophancy than Sonnet 4.6,” the company noted. “On our automated behavioral audit, which tests a wide range of misaligned behaviors such as cooperation with misuse and deception, Sonnet 5 scored lower (that is, safer) overall.”
It’s worth noting that Anthropic admits Sonnet 5 displays higher rates of “misaligned behavior” compared to Opus 4.8 and Claude Mythos, urging caution by users.
Safety tests for Sonnet 5 come at a critical time for Anthropic, with the company having launched Claude Mythos earlier this year as part of a gated preview with select industry partners.
How to access Sonnet 5
Claude Sonnet 5 is available across all plans from today, according to Anthropic, including Max, Team, and Enterprise users. It will also act as the default model for Free and Pro plans.
For Claude Code and Claude Platform users, Sonnet will come with an “introductory” pricing of $2 per million input tokens, and $10 per million output tokens until 31 August.
Thereafter, Anthropic said prices will rise to $3 and $15 across input and output tokens respectively.
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