You say "blue" twice!
Per Airbus one should call out both the color of the armed vertical mode, AND the new altitude target on the PFD. The FMA response by the PM is "checked", and the PM should repeat the set altitude target verbatim. So it should go something like this (remember the altitude is set prior to pulling):
PF (sets altitude): "FL300 blue".
PM: "FL300 blue".
PF (pulls altitude): "Thrust idle, open descent, alt blue".
PM: "Checked."
Alternative would be:
PF (sets and pulls): "Thrust idle, open descent, alt blue, FL300 blue".
PM: "Checked, FL300 blue".