A method for controlling a manufacturing process of a plant via a MES system comprising the following steps: a) providing the MES system with a catalogue of a tool model added to the personnel model, to the equipment model and the material model of the product definition model of the ISA-S95 standard; wherein the tool model comprises tool entities and tool methods on the tool entities, wherein the tool entities comprise engineering-time tool entities and run-time tool entities and wherein the tool methods comprise engineering-time tool methods and run-time tool methods; b) at engineering time or at run time, by a tool manager, exposing the tool model catalogue containing tool entities and tool methods, in order to allow user customization according to specific plant requirements, and storing information on the tool model data in a database; wherein the tool model comprises abstract entities defined at engineering time, selected from the group consisting of tool type entity, tool class entity, tool definition entity, bill of tools entity, bill of tool items entity and wherein the tool model additionally comprises a tool entity instantiating a physical object at runtime; c) at engineering time, defining specific engineering-time tool entities by invoking engineering-time tool methods; d) at run time, instantiating the specific tool entities into run-time tool objects with the creation of the correspondence between the tool database records and the tool physical objects of the specific plant; e) at run time, controlling the manufacturing process relative to physical plant tools by invoking the run-time tool methods on the run-time tool objects. a) providing the MES system with a catalogue of a tool model added to the personnel model, to the equipment model and the material model of the product definition model of the ISA-S95 standard; wherein the tool model comprises tool entities and tool methods on the tool entities, wherein the tool entities comprise engineering-time tool entities and run-time tool entities and wherein the tool methods comprise engineering-time tool methods and run-time tool methods; b) at engineering time or at run time, by a tool manager, exposing the tool model catalogue containing tool entities and tool methods, in order to allow user customization according to specific plant requirements, and storing information on the tool model data in a database; wherein the tool model comprises abstract entities defined at engineering time, selected from the group consisting of tool type entity, tool class entity, tool definition entity, bill of tools entity, bill of tool items entity and wherein the tool model additionally comprises a tool entity instantiating a physical object at runtime; c) at engineering time, defining specific engineering-time tool entities by invoking engineering-time tool methods; d) at run time, instantiating the specific tool entities into run-time tool objects with the creation of the correspondence between the tool database records and the tool physical objects of the specific plant; e) at run time, controlling the manufacturing process relative to physical plant tools by invoking the run-time tool methods on the run-time tool objects.