Skills are rusty - is rusty an adjective or an adverb?

Answer 1

In the sentence, 'My skills are rusty.', the word 'rusty' is an adjective called a predicate adjective (also called a subject complement), the adjective following a linking verb which modifies or restates the subject of the sentence (skills = rusty).

Answer 2

In this context, "rusty" is an adjective describing the condition of your skills. Adjectives are used to describe or modify nouns or pronouns, while adverbs typically modify verbs, adjectives, or other adverbs.