In CRM 2011, tool tips are minimal and typically repeat the display name attribute of the field.
These type of tool tips are useful for unlabeled UI, however most form fields have labels assigned to them and users need more information when entering or selecting data. Explanatory tooltips provide helpful text to address known user questions, explain terminology or concepts, and help end-users make good decisions to stay on task.
In CRM 2013, custom tool tips aim to improve your user experience by:
- Providing information on how to use and complete forms, right on the page
- Allowing your organization to display your business-specific information and processes to your users -- right in CRM forms.
You can display entity attribute “Description” as tool tips on fields, buttons, etc. on existing forms for customizable entities. This will work against OOB and custom attributes.
To update tool tips when you are customizing an entity or entity attribute simply edit the "Description" attribute via the Settings -> Customize the System
In the customazation interface you can work with the "Description" attribute through Form editor
or the field editor