1. A method, comprising: receiving process messages from a cluster tool used in a manufacturing process line via an interface communicating with said cluster tool, said cluster tool comprising a plurality of entities, wherein said process messages comprise tool-specific information specifying one of a plurality of available states for each of said entities; automatically determining a metric for a current total state of said cluster tool on the basis of a functional capacity of each entity and said process messages, wherein said plurality of available states comprises a productive state, a standby state, an engineering state, a scheduled down state, an unscheduled down state and a non-scheduled state, and wherein said plurality of available states are ranked in a hierarchy, and wherein said hierarchy has a ranking of said plurality of available states in the following order from lowest to highest priority: a productive state, a standby state, an engineering state, a scheduled down state, an unscheduled down state and a non-scheduled state.