Determine when to use plan mode vs direct execution

Plan mode is a Claude Code operating mode that restricts the agent to read-only actions, reading files, searching with Grep and Glob, and reasoning, while it explores the codebase and drafts an implementation plan. It cannot edit files or run state-changing commands until you approve.

You enter it interactively by pressing Shift+Tab to cycle permission modes (normal, auto-accept edits, plan mode), or non-interactively with claude --permission-mode plan. When Claude has a plan, it calls the ExitPlanMode tool to present it, and execution only begins after you approve. This approval gate is the entire point: exploration and design happen with zero risk of premature changes.

Contrast this with direct execution, the default mode, where Claude reads, edits, and runs commands in one continuous flow. Direct execution is faster for work you already understand but offers no design checkpoint before changes land.

Plan mode is designed for complex tasks: large-scale changes, multiple valid approaches, architectural decisions, and multi-file modifications. The strongest signals are architectural implications (service boundaries, module dependencies), migrations that touch many files (a library migration affecting 45+ files), or choosing between integration approaches that carry different infrastructure requirements.

The core benefit is safe codebase exploration and design before committing to changes, which prevents costly rework when a dependency or constraint is discovered late. If you cannot yet describe the exact edits, or several reasonable designs exist, that uncertainty is itself the trigger for plan mode.

Direct execution is appropriate for simple, well-scoped changes where the path is already clear: a single-file bug fix with a clear stack trace, or adding a date-validation conditional to one function. Forcing plan mode onto work like this only adds round trips and latency with no design benefit.

A useful rule of thumb: if you can state the exact change and it lives in one place, execute directly. The cost of plan mode is real, an extra approval cycle and more turns, so reserve it for tasks where the design is genuinely in question.

The two modes are not mutually exclusive across a single task. A common and recommended pattern is to use plan mode for the investigation and design phase, get the plan approved, then switch to direct execution to implement it.

For example, plan a library migration first (compatibility shims, call-site updates, rollout order), then execute the planned approach directly. The planning phase absorbs the uncertainty, and the execution phase runs fast because the scope and approach are now settled.

The Explore subagent is a read-only discovery subagent invoked via the Task tool. It runs verbose exploration in an isolated context and returns only a summary to the main conversation, which prevents context window exhaustion during multi-phase tasks.

Distinguish it from plan mode. Plan mode is an approval gate on the main agent, whereas the Explore subagent is a context-isolation technique. They compose well: during a plan-mode investigation you can dispatch Explore subagents so that raw file dumps and dependency traces never pollute the main context, keeping the main agent focused on high-level design.

Ask two questions. Is the scope known and localized to one place? If yes, execute directly. Does the task involve architectural decisions, many files, or competing valid approaches? If yes, use plan mode.

Do not defer the mode decision. Complexity that is already stated in the requirements is enough to justify plan mode upfront. The trap of beginning in direct execution and switching to plan mode only if complexity emerges fails because, by the time complexity surfaces, you may already have made edits that need reverting.