Is There a Class of Adjectives in Esperanto?

In English, there's no marking at all that adjectives get that relates to either verbs or nouns. Japanese has two classes of adjectives: a verb-like set and a noun-like set behave quite differently. Hopi turns adjectives into prefixes when they are modifying an noun. It can be difficult to come up with a definition of an adjective that applies correctly to all languages. Each language is going to have their own test.