Tags support has been added to 3 EC2Describe* API's(DescribeInstances, DescribeVolumes and DescribeSnapshots). Hence for the same 3 EC2Describe* API's filter support has been modified to included 3 tag related filters: tag-key,
tag-value and tag:key.
Verified the output of,
1. ec2-create-tags for all 4 supported ec2 resources(image, instance, volume and snapshot) with and without tag-value.
2. ec2-delete-tags for all types of created tags.
3. ec2-describe-tags with and without all supported filter.