In Japanese the specific grammatical classification of a word sometimes has more to do with how it is conjugated than with what semantic role it fulfills.
The two main types of adjectives are
形容詞 (i-adjectives) and
形容動詞 (na-adjectives). You can call both of those "adjectives" but that doesn't get you anywhere in terms of figuring out how to actually use them in a sentence, which turns out to be quite different.
Then there are no-adjectives like
黄色. I see these in Daijirin dictionary on Weblio marked as
名 ・形動, meaning "noun and/or adjective".
And there are a number of other types of adjectives as well, such as なる and たる adjectives, but those pop up pretty rarely.
So I would say the concept of "adjective" is not that useful in Japanese, because it's not specific enough and doesn't tell you how to use the word. Instead of asking "how should I use this adjective", I would suggest asking "is this an i-adjective, a na-adjective, or a no-adjective (or something else)?" and once you figure that out, you can use the relevant rules for that type of word.