What Claude Opus 4.8 Actually Changes If You’re Building Agents

I’ve been building AI agents for long enough now to have developed a healthy reflex: whenever a new frontier model drops, my first question isn’t “is it smarter?” It’s “does it change the shape of the code I have to write?” Most releases don’t. They nudge a benchmark, shave a few cents off a token, and the agent loop I wrote last quarter still looks the same the next morning. Claude Opus 4.8 is one of the rare ones that does change the shape. Anthropic shipped it on May 28, 2026, and on the surface it reads like a polish release - better coding, better tool use, better alignment numbers.