security concerns for tooltips

Question

We have a requirement to show the tooltips on ASP.Net WebApplication. This tooltips would contain the information about the Regular Expression. For eaxmple: First Name Textbox: Hover on this text box, there should be a tool tip that contains text like this - A-Aa-z0-9@# etc.

There are two options here:
Display the regex on the hover of textbox
Include a icon near to label. The Regex would be displayed on hover of that icon.

Wanted to know which option is best and why.