Anthropic released Claude Sonnet 4.6 yesterday and I switched this morning, moving from Opus 4.6 as my default in Claude Code. I’d been using Opus because it handled complex, multi-step tasks better, but I’ve always preferred Sonnet’s writing register. More direct, less padded.
After about an hour with Sonnet 4.6 I’m noticing a qualitative shift. The interaction feels more efficient; it seems to know when to stop. Anthropic reports that users preferred it to Opus 4.5 in 59% of cases and rated it “significantly less prone to overengineering and ‘laziness,’ and meaningfully better at instruction following.” That matches what I’m feeling.
The task that would usually make me reach for Opus: I asked Sonnet 4.6 to work through my Obsidian vault of nearly 6,000 notes — analyse file types, structure, and status, surface issues I’d raised, and identify ones I hadn’t. It produced a multi-stage plan and is working through it methodically. No obvious problems so far, and it flagged things I genuinely hadn’t considered. Previously that kind of sustained, multi-pass analysis across a large corpus was Opus territory. Maybe not anymore.
I’m not quite ready to tell it to implement each stage independently without me in the loop — but I’m closer to that than I expected to be after a single session.