Can I add gray-font text to a field, and have the text disappear when the user clicks in the field?

[Phil Bustin]

I would like to use an automation to add default text to the top of a custom text field (paragraph or limited).  Can either of the following properties occur for the default text?

   1) Appear as gray font in the field.

   2) Disappear as soon as the user clicks in the field, whether to enter text or paste copied           text.

Can either be done?

Related to that question: I noticed the behavior I described above in gray-font prompts in the Description field, but (unlike the Sprint field), I can't view Description in [project] > Settings > Issues > Custom Fields.  Where can I modify that Description default?