1. A system diagram model creation tool comprising: a plurality of glossary data sets stored on a memory device; and a heuristics data set stored on the memory device, wherein the heuristics data set includes a plurality of heuristic rules; a functional design creation module executable by a processor to: receive a processed requirements specification defining functionality of a system, wherein the processed requirements specification includes at least one processed requirements statement and at least one processed use case; retrieve the plurality of glossary data sets, and the heuristics data set; generate a plurality of functional design diagram components based on the at least one processed requirements statement, the at least one processed use case, at least one of the plurality of glossary data sets, and the plurality of heuristic rules, wherein the plurality of functional design components includes at the least one entity included in the system and at least one relationship associated with the at least one entity; generate a functional design diagram based on the functional design components, wherein the functional design diagram is representative of the system, and wherein the functional design diagram includes at least one diagram element representative of the at least one entity and a relationship indicator representative of the at least one relationship; and transmit the modified functional design diagram to at least one display.