Use "ultrathink" to Unlock Maximum Reasoning
The ultrathink keyword instructs Claude to spend its maximum internal reasoning budget before responding — significantly more deliberate than a standard reply.
ultrathink
I have a race condition in my distributed job queue where two workers
occasionally process the same job. The queue uses Redis LPOP. Explain
exactly what's happening and propose a fix using atomic Redis operations.
Claude will spend significantly more tokens reasoning through the problem before giving you an answer — useful for architecture decisions, subtle bugs, and complex algorithm design where a fast answer is worse than a thoughtful one.
The reasoning hierarchy goes from lightest to heaviest:
think → think hard → think harder → ultrathink
Each step allocates more internal reasoning budget. For everyday questions the default is fine, but when you're stuck on something genuinely complex, prepending ultrathink to your prompt often catches angles a quick response misses.
Use it sparingly — the extra reasoning takes more time and tokens. Reserve it for the problems that have kept you stuck for hours, not the ones you could solve with a quick search.
Save ultrathink for the problems that actually deserve it — it's worth the wait.
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Before asking Claude to scaffold a new feature, point it at your existing code first — it will match your naming, structure, error handling, and test patterns exactly rather than defaulting to framework boilerplate.
Give Claude the full picture upfront before it writes any code, so it builds the right thing the first time with fewer correction rounds.
Complex prompts are unreadable as escaped single-liners. Use shell HEREDOCs to write clean, structured prompts directly in your scripts.