ansible-later is a best practice scanner and linting tool. In most cases, if you write Ansible roles in a team, it helps to have a coding or best practice guideline in place. This will make Ansible roles more readable for all maintainers and can reduce the troubleshooting time. While ansible-later aims to be a fast and easy to use linting tool for your Ansible resources, it might not be that feature completed as required in some situations. If you need a more in-depth analysis you can take a look at ansible-lint.
ansible-later does not ensure that your role will work as expected. For Deployment test you can use other tools like molecule.