Output

± % ansible-playbook -i deploy_conf/localhost test.yml

PLAY: ***************************************************************************

TASK [setup] ********************************************************************
ok: [localhost]

TASK [debug msg=Hello] **********************************************************
fatal: [localhost]: FAILED! => {"failed": true, "stdout": ""}

NO MORE HOSTS LEFT **************************************************************

PLAY RECAP **********************************************************************
localhost                  : ok=1    changed=0    unreachable=0    failed=1

test.yml

---
- hosts: localhost
  connection: local
  vars:
    my_var: { "something": "{{ truth3 }}" }
  tasks:
    - debug: msg="Hello"
      when: truth3 is defined and my_var is defined