Add Character Limit

I have a field where I need to specify a character limit using apaces.
How can I achieve this?

<Field displayName="Account Description" displayType="textarea" helpKey="Enter a description up to 256 characters, including spaces and special characters." name="description" type="string"/>

You may have to use a validation script to ensure that your form field does not get submitted when it has more than the character limit. Here is a working sample for a validation script present on the form field.

             <ValidationScript>
              <Source>
                try {
                import sailpoint.object.Application;
                import sailpoint.object.Identity;

                if(null != accountName &amp;&amp; accountName.length() >20){
                return "Account Name for AD account cannot be more than 20 characters";
                }
                if(null != accountName &amp;&amp; accountName.matches(".*\\s+.*")){
                return "Account Name for AD account cannot have whitespaces";
                }
                } catch(Exception e){
                return null;
                }
                return null;
              </Source>
            </ValidationScript>