What is Plan And Execute Pattern?
Also called plan and solve, planner executor.
Plan and execute is an agent design in which a planning step produces an explicit multi-step plan up front, and a separate execution step carries out those steps in order, optionally replanning when a step fails. It contrasts with interleaved designs that decide only the next single action after observing the previous result.
The pattern separates two different kinds of work. Planning is expensive reasoning done once over the whole problem, while execution is cheap and repetitive. Because the plan exists as data before anything runs, it can be inspected, edited, approved by a person, or cached and reused for similar requests, none of which is possible when the next action is chosen only in the moment.
Cost and latency usually improve. A single strong planning call can be followed by many smaller execution calls, and steps that do not depend on each other can run in parallel. The explicit plan also gives progress reporting a real basis, since step three of seven is a fact about the plan rather than an estimate.
The weakness is brittleness. A plan written before any tool has run encodes assumptions about the world that may be wrong, so a step can fail because a file, record, or permission does not exist as assumed. Practical implementations add a replanning loop, returning to the planner with the failure observation attached rather than aborting.
How much to plan is a design decision rather than a settled answer. Overly detailed plans waste effort on steps that later change, while overly coarse ones push all the real decisions into execution and lose the pattern's benefits. Many systems plan at the level of goals and leave tool choice to the executor.
Key points
- Plan is produced as inspectable data before execution
- Enables approval, caching, parallelism, and real progress reporting
- Plans built on untested assumptions are brittle
- Replanning on failure is a required addition
- Plan granularity is a tuning decision, not a fixed rule
In practice
Asked to onboard a new client, an agent first emits a plan: create the folder, copy three templates, populate them from the intake form, then schedule a kickoff. A reviewer approves the plan before anything runs. Step two fails because one template was renamed, so the executor returns the failure to the planner, which substitutes the current template and resumes at step two.