Custom tooltips in CRM 2013
In CRM 2013, we now have OOB way to specify custom tool tips for the fields using the description text.
The description appearing as Tool Tip
To achieve the same in CRM 2011 we had to go the unsupported way.
Check this post.
https://crmxpg.nl/wp/2010/10/14/display-tooltips-for-fields-in-ms-crm-part-1/
Cheers,
Shraddha Dhingra