Converting string to integer in Ansible Playbook

here's what I did to make it work:

---
- name: answer serverfault
  hosts: all
  become: yes

  tasks:
    - name: Get message_count
      shell: ls /tmp/empty | wc -l
      register: tmp_count
      delegate_to: localhost
    - debug: var=tmp_count.stdout
    - name: do something else when tmp_count.stdout == 0
      shell: echo "I am doing it"
      delegate_to: localhost
      when: tmp_count.stdout | int == 0

and here's the playbook run result:

ripper@mini-ripper:~/Devel/ansible$ ansip ./test_playbook.yml  -i localhost,

PLAY [answer serverfault] **************************************************************************************************************************************************************************************

TASK [Gathering Facts] ********************************************************************************************************************************************************************************************
[WARNING]: Platform linux on host localhost is using the discovered Python interpreter at /usr/bin/python, but future installation of another Python interpreter could change this. See
https://docs.ansible.com/ansible/2.9/reference_appendices/interpreter_discovery.html for more information.
ok: [localhost]

TASK [Get message_count] ******************************************************************************************************************************************************************************************
changed: [localhost -> localhost]

TASK [debug] ******************************************************************************************************************************************************************************************************
ok: [localhost] => {
    "tmp_count.stdout": "0"
}

TASK [do something else when tmp_count.stdout == 0] ***************************************************************************************************************************************************************
changed: [localhost -> localhost]

PLAY RECAP ********************************************************************************************************************************************************************************************************
localhost                  : ok=4    changed=2    unreachable=0    failed=0    skipped=0    rescued=0    ignored=0   

so to recap:

• you should check if the register variable isn't more complex structure - it usually is
• you don't need another custom fact
• you need to convert your variable without using {{ }} in when condition