Since zf2 come's with an Twitter Bootstrap implementation you could just use the Tooltip functionality. I personally do not use anotation's in my forms for various reasons, one being the performance hit you take.
within your YourForm.php
just set some data attributes and you should be good to go:
$this->add(array(
'name' => 'submit',
'type' => 'Submit',
'attributes' => array(
'value' => 'Save',
'id' => 'submitbutton',
'data-toggle' => 'tooltip',
'data-placement' => 'left',
'title' => 'Press me I am a button :D',
),
));
The annotation equivalent would be:
* @Annotation\Attributes({"data-toggle":"tooltip", "data-placement":"left", "title":"Press me I am a button :D"})