Hi @AlexanderFalkenberg , unfortunately sendMediaGroup method doesn't support the "caption" attribute (https://core.telegram.org/bots/api#sendmediagroup) like other attachments. You can try with the "reply_parameters" attribute, this will link the MediaGroup to a message like this :

$last_message_id = $telegraphChat->message('message')->send()->telegraphMessageId();

$telegraphChat->mediaGroup([
 [
 'type' => 'photo',
 'media' => 'https://test.jpg',
 ],
 [
 'type' => 'photo',
 'media' => 'https://test.jpg',
 ],
])->withData('reply_parameters', ['message_id' => $last_message_id])->send();

Actually it is possible, just add caption key to the first only attachment.