Hook alter mail params needs more info (id)

Trying to use the hookAlterMailParams & I have no way of identifying which reminder it relates to

the only data I have is

(
[groupName] => Scheduled Reminder Sender
[from] => me <test@EXAMPLEr.ORG>
[toName] => Jerome Bachman
[toEmail] => jeromeb@notmail.co.in
[subject] => jjj
[text] => kk
[html] => <p>kk</p>

[returnPath] => test@EXAMPLEr.ORG
)

It seems extra params could be added pretty easily and they would be passed straight through ie.

// set up the parameters for CRM_Utils_Mail::send
$mailParams = array(
'groupName' => 'Scheduled Reminder Sender',
'from' => $from,
'toName' => $contact['display_name'],
'toEmail' => $email,
'subject' => $messageSubject,
);

could also have

$mailParams['entity'] = 'action_schedule';
$mailParams['entity_id'] = 2;

I note Activity::sendMessage relates to an activity entity - so this would work ok here.

We could also add something like entity_params = array() - anything particular to this calling of the hook - but I don't have a specific usage for that if we add the entity & entity id