searchable media tags

I’m trying to make it so that authors can tag their media and search for media using those tags. Currently I am running into two problems with my code:

1. The Media Tags page doesn’t show up in the Dashboard for anyone but the administrator
2. Tagged pictures don’t show up in search!

Here is my code:

<?php

/**
// register new taxonomy which applies to attachments
function wptp_add_media_tag_taxonomy() {
    $labels = array(
        'name'              => 'Media Tags',
        'singular_name'     => 'Media Tag',
        'search_items'      => 'Search Media Tags',
        'all_items'         => 'All Media Tags',
        'parent_item'       => 'Parent Media Tag',
        'parent_item_colon' => 'Parent Media Tag:',
        'edit_item'         => 'Edit Media Tag',
        'update_item'       => 'Update Media Tag',
        'add_new_item'      => 'Add New Media Tag',
        'new_item_name'     => 'New Media Tag Name',
        'menu_name'         => 'Media Tag',
    );

    $args = array(
        'labels' => $labels,
        'hierarchical' => true,
        'query_var' => 'true',
        'rewrite' => 'true',
        'show_admin_column' => 'true',
    );

    register_taxonomy( 'media_tag', 'attachment', $args );
}
add_action( 'init', 'wptp_add_media_tag_taxonomy' );

Is there a better way to do this? It seems odd to me that there isn’t a good way to tag and search photos.