Claude Opus 4.8: What Changed, and How I'll Test It
Opus 4.8 is not the main event. It is the model that teaches you how to work before Mythos arrives.
TL;DR
Claude Opus 4.8 is Anthropic’s most capable widely available model, released May 28, 2026, at the same price as Opus 4.7: $5 per million input tokens and $25 per million output tokens. The API model string is claude-opus-4-8. The headline upgrade is judgment, not raw intelligence: Anthropic says it is around four times less likely than Opus 4.7 to let flaws in its own code pass unremarked. Three things ship alongside it: effort control on claude.ai, Dynamic Workflows in Claude Code, and a Fast mode that runs at 2.5x speed for three times less than it cost on previous Opus models. Opus 4.8 is a bridge to Claude Mythos, Anthropic’s more powerful model still gated for cybersecurity reasons under Project Glasswing.
Just when I thought I’d get a calm evening with For All Mankind, Opus 4.8 happened.
I went from dynamic space missions to dynamic workflows. I adapted immediately, because my plans are dynamic too.
Here’s what changed in forty-one days.
That’s how long Opus 4.7 lasted before Anthropic moved on to Opus 4.8.
Hey, I’m Karo Zieminski 🤗
AI Product Manager and builder.
I write Product with Attitude, an AI newsletter for thousands of subscribers developing critical AI literacy the only way it sticks: through practice.
Why trust this analysis: I’m looking at Claude Opus 4.8 from the builder’s seat: what changed, what breaks, what costs more, what needs testing, and what should not be trusted.
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