watchful vs argus-eyed

watchful and argus-eyed both are adjectives.

Word	Noun	Adjective	Verb	Adverb
watchful	No	Yes	No	No
argus-eyed	No	Yes	No	No

As adjectives, watchful and argus-eyed are synonyms defined as:

watchful and argus-eyed: carefully observant or attentive; on the lookout for possible danger

Other synonyms of watchful include open-eyed, vigilant, wakeful.

watchful (adjective)	argus-eyed (adjective)
engaged in or accustomed to close observation	carefully observant or attentive; on the lookout for possible danger
experiencing or accompanied by sleeplessness	having very keen vision
carefully observant or attentive; on the lookout for possible danger