This is confusing. ULTRATHINK is a step below /effort max?
ULTRATHINK triggers high effort. /effort max is above high. Calling it ULTRATHINK sounds like it would be the highest mode. If someone has max set and types ULTRATHINK, they're lowering their effort for that turn.
For anyone reading this trying to fix the quality issues, here's what I landed on in ~/.claude/settings.json:
The env field in settings.json persists across sessions without needing /effort max every time.
DISABLE_ADAPTIVE_THINKING is key. That's the system that decides "this looks easy, I'll think less" - and it's frequently wrong. Disabling it gives you a fixed high budget every turn instead of letting the model shortchange itself.
The docs say that CLAUDE_CODE_EFFORT_LEVEL controls adaptive reasoning intensity, and CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING bypasses that entirely in favor of a fixed budget via MAX_THINKING_TOKENS. So setting both is contradictory. If true, disabling adaptive thinking would override what effort level is trying to do.
So if it bypasses, is the optimal setting for performance setting effort level to max, keeping adaptive on? I try to avoid letting the model decide what is unimportant and needs less thought
Nothing super noticeable. I've reached 35% in sessions on the 20x plan. Before these changes, 25-30% was pretty normal. I think these changes are best for people who are just past the 5x usage plan, but might be harder to manage if you already have to throttle usage to stay under limits.
I'd still recommend turning off sub agents entirely because it doesn't seem you can control them with /effort and I always find the output to be better with agents off.
ULTRATHINK triggers high effort. /effort max is above high. Calling it ULTRATHINK sounds like it would be the highest mode. If someone has max set and types ULTRATHINK, they're lowering their effort for that turn.
For anyone reading this trying to fix the quality issues, here's what I landed on in ~/.claude/settings.json:
The env field in settings.json persists across sessions without needing /effort max every time.DISABLE_ADAPTIVE_THINKING is key. That's the system that decides "this looks easy, I'll think less" - and it's frequently wrong. Disabling it gives you a fixed high budget every turn instead of letting the model shortchange itself.