I'm getting Validation error messages with
$workers = array('Filters' => array(array('Name' => 'Tags', array(array('Key' => 'Name', 'Values' => array('mworker'))))));
$list = $ec2Client->describeInstances($workers);
Error Detail:
[Filters][0][Filter] must be an array of properties. Got a numerically indexed array.'
This is with SDK2