aws cli – Is there any rhyme or reason behind when to use list- and when to use describe- for the AWS CLI?

For the AWS CLI the right command is:

aws ec2 describe-key-pairs

But not:

aws ec2 describe-key-pairs

But there is:

aws ecs list-clusters

My current workflow is:

  1. Guess
  2. Get it wrong
  3. Change
  4. Get it wrong
  5. Look in the help
  6. Realize a made a typo like descrbe
  7. Go back to my first guess

But I wish I knew some reason to help choose between list-foo or describe-foo.