This roles installs Mysql database

Any pre-requisites that may not be covered by Ansible itself or the role should be mentioned here. For instance, if the role uses the EC2 module, it may be a good idea to mention in this section that the boto package is required.

Python must be installed

Including an example of how to use your role (for instance, with variables passed in as parameters) is always nice for users too:

- hosts: servers
  roles:
     - mysql_db

BSD

An optional section for the role authors to include contact information, or a website (HTML is not allowed).