Pithy summary for comonad. (Where a monad is a 'type for impure computation')

Question

In terms of pithy summaries - this description of Monads seems to win - describing them as a 'type for impure computation'.

What is an equivalent pithy (one-sentence) description of a comonad?

Answer 1

"A type for context-dependent computation"

Alternatively, a better "pithy description" for monads might be a 'type for output impurity', in which case then the pithy description for comonads is a 'type for input impurity'.

(If you are interested in comonads, some more introduction is given in some talks slides of mine: http://www.cl.cam.ac.uk/~dao29/talks/comonads-and-codo-talk-dorchard-2011.pdf)