Definition
The planner-executor pattern, also called plan-then-execute, is an agentic design that separates reasoning from action. A planner component first formulates a complete multi-step plan for a complex goal, and a distinct executor then carries out those steps one by one, invoking tools or sub-agents and reporting results. This explicit decoupling of planning from doing is the pattern's defining trait and the source of its main benefits.
Why separate the roles
Forcing the model to commit to a plan before acting makes its intentions inspectable: you can log, validate, or even require approval of the plan before any step runs. It also tends to keep long tasks coherent, since the executor follows an agreed roadmap rather than re-deciding the whole strategy at every turn. A reviewer step is often added so the system can re-plan when reality diverges from the plan.
Contrast with reactive loops
A purely reactive agent interleaves thinking and acting at each step and adapts continuously, which is flexible but can wander. The planner-executor pattern trades some of that adaptivity for structure and predictability. The cost is higher latency and more model calls, because planning and execution are separate phases and re-planning adds cycles.
This pattern is a common building block inside a multi-agent system, where a planner agent supervises one or more executor agents, and it relies on tool use to act. Because the plan is explicit, it pairs naturally with a human-in-the-loop approval gate. D-Central documents these patterns for operators running agents on their own infrastructure.
In Simple Terms
The planner-executor pattern, also called plan-then-execute, is an agentic design that separates reasoning from action. A planner component first formulates a complete multi-step plan for…