Okay, I don't know if this is helpful or not, but I consider the distinction between adjectives and adverbs in German to a big extent arbitrary. There's few adverbs I can think of that can't act as an adjective (among them "vielleicht" - "maybe"). Depending on which part of speech it modifies, "vorsichtig" can mean "careful" or "carefully", except that before a noun it has to follow the noun's gender with its ending.

Incidentally, I believe there's vestiges of this situation in English (and I think it might apply to at least all of the European branch of the Indoeuropean family), when people respond to the question "How are you doing?" with "I'm doing good." And you might be inclined to correct that response to "I'm doing well." Which, in my opinion, is an artificial influence of a movement somewhere in the 18th or 19th century to make English behave more like the noble Latin, whereas by all signs a hard distinction between adverbs and adjectives doesn't come to it naturally.

And, of course, that same conversation in German would go like this: "Wie geht's dir?" "Es geht mir gut."