Introducing Claude Sonnet 4.6 (https://www.anthropic.com/news/claude-sonnet-4-6)

Sonnet 4.6 is out today, and Anthropic claim it offers similar performance to November’s Opus 4.5 (https://simonwillison.net/2025/Nov/24/claude-opus/) while maintaining the Sonnet pricing of $3/million input and $15/million output tokens (the Opus models are $5/$25). Here’s the system card PDF (https://www-cdn.anthropic.com/78073f739564e986ff3e28522761a7a0b4484f84.pdf).

I just released llm-anthropic 0.24 (https://github.com/simonw/llm-anthropic/releases/tag/0.24) with support for both Sonnet 4.6 and Opus 4.6. Claude Code did most of the work (https://github.com/simonw/llm-anthropic/pull/65) - the new models had a fiddly amount of extra details around adaptive thinking and no longer supporting prefixes, as described in Anthropic’s migration guide (https://platform.claude.com/docs/en/about-claude/models/migration-guide).

Here’s what I got (https://gist.github.com/simonw/b185576a95e9321b441f0a4dfc0e297c) from:

uvx –with llm-anthropic llm ‘Generate an SVG of a pelican riding a bicycle’ -m claude-sonnet-4.6

The SVG comments include:

I tried a second time and also got a top hat. Sonnet 4.6 apparently loves top hats!

For comparison, here’s the pelican Opus 4.5 drew me in November ((https://simonwillison.net/2025/Nov/24/claude-opus/)):

And here’s Anthropic’s current best pelican, drawn by Opus 4.6 on February 5th (https://simonwillison.net/2026/Feb/5/two-new-models/):

Opus 4.6 produces the best pelican beak/pouch. I do think the top hat from Sonnet 4.6 is a nice touch though.

Via Hacker News (https://news.ycombinator.com/item?id=47050488)

Tags: ai (https://simonwillison.net/tags/ai), generative-ai (https://simonwillison.net/tags/generative-ai), llms (https://simonwillison.net/tags/llms), llm (https://simonwillison.net/tags/llm), anthropic (https://simonwillison.net/tags/anthropic), claude (https://simonwillison.net/tags/claude), llm-pricing (https://simonwillison.net/tags/llm-pricing), pelican-riding-a-bicycle (https://simonwillison.net/tags/pelican-riding-a-bicycle), llm-release (https://simonwillison.net/tags/llm-release), claude-code (https://simonwillison.net/tags/claude-code)