SSH in shell command

I am new to ansible, i have the script in the remote machine and the script name is ssh.sh which contains below lines to ssh into some another server and run the script,

ssh @${server} "sh /tmp/script.sh"

the question is if i use shell module to call to the script ssh.sh in the playbook as below, will the ssh command with the above line will work or not???

- hosts: all
  tasks:
    - name: invoke the script
      shell: sh ssh.sh
      register: result

So what's the purpose of this task and why do you need Ansible for it?

Regards
         Racke