Press Shift+Tab twice in Claude Code to toggle Plan Mode. In this mode, Claude only performs read-only operations. It explores files, analyzes architecture, and creates a detailed implementation plan without writing a single line of code.
The “Rev the Engine” Technique
Power users take Plan Mode further with iterative plan refinement:
- Enter Plan Mode (Shift+Tab twice)
- Ask Claude to create an implementation plan
- Ask Claude to critique its own plan for missing edge cases, redundant steps, and ordering inefficiencies
- Repeat step 3 until the plan is solid
- Exit Plan Mode and say “execute the plan”
> Plan how to add rate limiting to our API endpoints.
> Now critique this plan. What edge cases are missing? What's the optimal ordering?
> Good. Now execute the plan.This pushes Claude through multiple thinking cycles, often catching issues that a single pass would miss. The Anthropic team themselves recommend investing heavily in the plan so Claude can one-shot the implementation.
When to Use Plan Mode
- Exploring an unfamiliar codebase
- Planning a multi-file refactor
- Reviewing code without risk of accidental changes
- Understanding dependencies before making breaking changes