AI model: Opus 5 from Anthropic

 Introducing Claude Opus 5 \ Anthropic

"It’s a thoughtful and proactive model that comes close to the frontier intelligence of Claude Fable 5 at half the price.

On coding and knowledge work evaluations like Frontier-Bench and GDPval-AA, Opus 5 is the new state-of-the-art, though it remains behind Mythos 5 on cybersecurity tasks.

requires update and restart of claude code to get new version

Opus 5 in Claude Code: the model changed on its own, your settings didn't | wmedia.es

claude update claude --version # 2.1.219 (Claude Code)

Until now, switching to a new model reshuffled your effort: the first time you ran Fable 5, Opus 4.8, or Opus 4.7, Claude Code applied that model's default level even if you had set another one, and held it across sessions until you made an explicit choice.

Opus 5 has no such hold: the level you had set carries over. If you once dropped to low to spend less, your brand-new Opus 5 starts on low. The model's own default is high.

/effort         # opens the slider and shows the active level
/effort auto    # back to the model default (high on Opus 5)