Prefill Text Editor Only for Specific Post Type

I’ve found a way to set the default content for the text editor for all posts:

add_filter( 'default_content', 'my_editor_content' );

function my_editor_content( $str ) {
	$str = "Enter <strong>description</strong> here.";
	return $str;
};

However, I only want to use this filter for a custom post-type that I’ve created. Is there a way to register filters for only certain post-types?