Version 4 supported
This version of Silverstripe CMS is still supported though will not receive any additional features. Go to documentation for the most recent stable version.

How to Show Help Text on CMS Form Fields

Sometimes you need to express more context for a form field than is suitable for its <label> element. The CMS provides you with an easy way to transform form field attributes into help text shown alongside the field, a tooltip which shows on demand, or toggleable description text.

The FormField->setDescription() method will add a <span class="description"> at the last position within the field, and expects unescaped HTML content.

use SilverStripe\Forms\TextField;

TextField::create('MyText', 'My Text Label')
    ->setDescription('More <strong>detailed</strong> help');

Sometimes a field requires a longer description to provide the user with context. Another option you have available is making the field's description togglable. This keeps the UI tidy by hiding the description until the user requests more information by clicking the 'info' icon displayed alongside the field.

TextField::create('MyText', 'My Text Label')
    ->setDescription('More <strong>detailed</strong> help')

Note: For more advanced help text we recommend using Custom form field templates;