Cool
The usage of cool as a general positive epithet or interjection has been part of English slang since World War II, and has been incorporated into other languages, such as French and German. Use of the term in this manner has its origin in African-American slang, in which, among other things, it can mean “excellent”, “intriguing”, or “superlative,” having first been recorded in written English in the early 1930s. More contemporary synonyms include groovy, fresh, and deck. (See Cool (aesthetic).)

Reference Wikipedia/cool

Definition of Tool - A tool is a device that provides a mechanical or mental advantage in accomplishing a task. Fitting into this definition we have software devices and hardware devices for accomplishing tasks in relation to computing.