Adverbs of degree answer the question "To what degree?" Those of manner answer the question "In what manner?" (That's pretty obvious, I suppose!)
So is it, "To what degree is it written?" - "Well." ???
Or is it, "In what manner is it written?" - "Well." ???
Try this one:
It is written very well. What kind of adverb is "very"?
To what degree is it writt