The Agent RaceJune 30, 2026via Simon Willison
What's new in Claude Sonnet 5
Why it matters
Anthropic's incremental refresh to Sonnet expands the mid-tier model portfolio, signaling continued competition in the density-vs-capability tradeoff that drives enterprise AI adoption decisions.
Key signals
- Claude Sonnet 5 release
- Published June 30, 2026
- Anthropic model tier update
- Source: Simon Willison (reputable AI analyst)
The hook
Claude Sonnet 5 just shipped. Here's what changed.