This is probably the most useful feature of amtool: the ability to validate the syntax and schema of our Alertmanager configuration file and referenced template files. You can test the check-config sub-command by following this example:

vagrant@alertmanager02:~$ amtool check-config /etc/alertmanager/alertmanager.yml 
Checking '/etc/alertmanager/alertmanager.yml' SUCCESS
Found:
 - global config
 - route
 - 1 inhibit rules
 - 8 receivers
 - 1 templates
  SUCCESS

This type of validation is quite easy to automate and should be done after any configuration change, but before reloading the Alertmanager instance, thereby preventing most types of configuration issues.