tool vs work on

tool is a noun but work on is not a noun.

Word	Noun	Adjective	Verb	Adverb
tool	Yes	No	Yes	No
work on	No	No	Yes	No

As verbs, work on is a hypernym of tool; that is, work on is a word with a broader meaning than tool:

Other hypernyms of tool include process, work.

tool (noun)	work on (noun)
the means whereby some act is accomplished
an implement used in the practice of a vocation
obscene terms for penis
a person who is controlled by others and is used to perform unpleasant or dishonest tasks for someone else

tool (verb)	work on (verb)
work with a tool	shape, form, or improve a material
ride in a car with no particular goal and just for the pleasure of it	to exert effort in order to do, make, or perform something
drive
furnish with tools