The planner is responsible for decomposing a high-level objective into discrete, sequenced steps. Given a goal like processing a vendor invoice, the planner decides to extract the data, validate against the purchase order, check for duplicates, and route for approval if the amount exceeds a threshold.
A planner allows an agent to handle novel goals by reasoning about what needs to happen and in what order, rather than only handling tasks it has seen exactly before. It also means the agent can revise mid-execution if results change the picture — which is what makes agentic systems genuinely adaptive rather than just automated.
