Model releaseHigh global significanceConfirmed confidence
Anthropic releases Claude Opus 4.5
A half-step 4.5 upgrade to Opus that strengthens deep reasoning while maintaining long-form generation quality.
What happened
Event details
Claude Opus 4.5 is a half-generation upgrade that improves deep logical reasoning while preserving long-form generation quality. Anthropic released the closed-source model on November 24, 2025; the parameter count is undisclosed and it is an autoregressive Transformer. The primary source is "Introducing Claude Opus 4.5."
Assessment
Why it matters
Rated on the impact-v1 six-axis scale: technical 4/5, market 4/5, ecosystem 3/5, policy & social 1/5, scope 4/5, durability 4/5.
78/100Global significance score. Regional effects are recorded only when the evidence supports a meaningful difference.