Plan & Execute (Agent Pattern)

ReAct thinks before every single action — flexible, but it can wander and burn many LLM calls on complex tasks. Plan & Execute takes a different approach: plan the whole task upfront, then execute the steps. Separating planning from execution makes agents more efficient and keeps them on-goal for long, structured tasks.

💡 In one line: Plan & Execute makes a complete plan upfront, then carries out each step — separating the planner from the executor.

What is Plan & Execute?

It's a pattern that separates planning from execution. A Planner produces a full multi-step plan in one go; an Executor then carries out each step (calling tools as needed). If reality diverges from the plan, an optional re-planner revises the remaining steps.

vs. ReAct

Architecture & Components

• Planner — produces the full plan (ordered steps).
• Plan — the list of steps to execute.
• Executor — carries out each step (may use tools, or even ReAct within a step).
• Re-planner (optional) — revises the remaining steps.

The Flow

Why Use It

• Complex, multi-step, structured tasks with a knowable shape.
• Less wandering — the plan keeps the agent on track.
• Fewer planning calls — it plans once instead of re-thinking every step.
• More predictable on long tasks.

Re-planning

Upfront plans meet reality — a step may fail or new information may appear. Allowing the agent to revise the remaining steps turns a brittle plan into a robust one. The common hybrid is plan → execute → re-plan.

Trade-offs

• The upfront plan may be wrong or incomplete.
• Less adaptive than pure ReAct in the moment.
• Planner quality is critical, and it's rigid without re-planning.

When to Use It (vs. ReAct)

• Known-structure, complex, long tasks → Plan & Execute.
• Dynamic, exploratory, simple tasks → ReAct.
• Often combined: the executor runs ReAct inside each step.

Best Practices

• Allow re-planning on failure or new info.
• Keep steps verifiable.
• Use ReAct within steps for local adaptivity.
• Validate the plan before executing.

Summary

• Plan & Execute plans the whole task upfront, then executes step by step.
• It separates the Planner from the Executor (with optional re-planner).
• It's efficient and on-goal for complex, structured tasks — where ReAct may wander.
• Its risk is a wrong upfront plan, so re-planning is key.
• Use it for structured tasks; use ReAct for dynamic ones — or combine them. EOF echo created