Playbook result with error and another file included is the playbook itself.

gistfile1.txt

[mikecali@rhel-tower vm_disk_add]$ ansible-playbook tasks/add_disks.yml -vvvv
Using /etc/ansible/ansible.cfg as config file
Loading callback plugin default of type stdout, v2.0 from /usr/lib/python2.7/site-packages/ansible/plugins/callback/__init__.pyc

PLAYBOOK: add_disks.yml ********************************************************
1 plays in tasks/add_disks.yml

PLAY [Reconfigure VM Filesystem] ***********************************************

TASK [Reconfigure Reconfigure VM Filesystem] ***********************************
task path: /home/mikecali/mike-personal/vm_disk_add/tasks/add_disks.yml:26
Using module file /usr/lib/python2.7/site-packages/ansible/modules/core/cloud/vmware/vsphere_guest.py
<127.0.0.1> ESTABLISH LOCAL CONNECTION FOR USER: mikecali
<127.0.0.1> EXEC /bin/sh -c '( umask 77 && mkdir -p "` echo $HOME/.ansible/tmp/ansible-tmp-1481678610.17-273194120531311 `" && echo ansible-tmp-1481678610.17-273194120531311="` echo $HOME/.ansible/tmp/ansible-tmp-1481678610.17-273194120531311 `" ) && sleep 0'
<127.0.0.1> PUT /tmp/tmpE14O0U TO /home/mikecali/.ansible/tmp/ansible-tmp-1481678610.17-273194120531311/vsphere_guest.py
<127.0.0.1> EXEC /bin/sh -c 'chmod u+x /home/mikecali/.ansible/tmp/ansible-tmp-1481678610.17-273194120531311/ /home/mikecali/.ansible/tmp/ansible-tmp-1481678610.17-273194120531311/vsphere_guest.py && sleep 0'
<127.0.0.1> EXEC /bin/sh -c '/usr/bin/python /home/mikecali/.ansible/tmp/ansible-tmp-1481678610.17-273194120531311/vsphere_guest.py; rm -rf "/home/mikecali/.ansible/tmp/ansible-tmp-1481678610.17-273194120531311/" > /dev/null 2>&1 && sleep 0'
fatal: [localhost]: FAILED! => {
    "changed": false, 
    "failed": true, 
    "invocation": {
        "module_args": {
            "cluster": null, 
            "esxi": {
                "datacenter": "ALABS-Wellington", 
                "hostname": "172.17.203.4"
            }, 
            "force": true, 
            "from_template": null, 
            "guest": "RHEL-jmt", 
            "password": "VALUE_SPECIFIED_IN_NO_LOG_PARAMETER", 
            "power_on_after_clone": true, 
            "resource_pool": null, 
            "snapshot_to_clone": null, 
            "state": "reconfigured", 
            "template_src": null, 
            "username": "administrator@vsphere.local", 
            "validate_certs": false, 
            "vcenter_hostname": "172.17.203.6", 
            "vm_disk": {
                "disk1": {
                    "datastore": "VM-Datastore-1", 
                    "size_gb": 31, 
                    "type": "thin"
                }, 
                "disk2": {
                    "datastore": "VM-Datastore-1", 
                    "size_gb": 10, 
                    "type": "thin"
                }
            }, 
            "vm_extra_config": {
                "mem.hotadd": true, 
                "vcpu.hotadd": true
            }, 
            "vm_hardware": {
                "memory_mb": "1024", 
                "num_cpus": "1", 
                "osid": "RH7", 
                "scsi": "paravirtual"
            }, 
            "vm_hw_version": null, 
            "vm_nic": {
                "nic1": {
                    "network": "VM Network", 
                    "network_type": "standard", 
                    "type": "vmxnet3"
                }
            }, 
            "vmware_guest_facts": null
        }, 
        "module_name": "vsphere_guest"
    }, 
    "msg": "Error reconfiguring vm: Invalid configuration for device '0'., [{'size_gb': 10, 'type': 'thin', 'datastore': 'VM-Datastore-1'}]"
}

gistfile2.txt

---
- name: Reconfigure VM Filesystem
  hosts: localhost
  connection: local
  gather_facts: False

  vars:
    ip_addr: "172.17.203.24"
    netmask: "255.255.255.192"
    gateway: "172.17.203.1"
    net_interface: eth0
    vcenter_username: "administrator@vsphere.local"
    vcenter_password: "xxxx"
    alabs_cluster: "NextGen-Cluster"
    alabs_dc: "ALABS-Wellington"
    alabs_dns: "172.17.171.173"
    alabs_domain: "alabs.datacom.co.nz"
    datastore: "VM-Datastore-1"
    folder: Template
    vm_name: RHEL-jmt
  

  tasks:
    - name: Reconfigure Reconfigure VM Filesystem
      vsphere_guest:
        validate_certs: False
        vcenter_hostname: 172.17.203.6
        username: "administrator@vsphere.local"
        password: "xxxx"
        guest: "{{ vm_name }}"
        force: yes
        state: reconfigured
        vm_extra_config:
          vcpu.hotadd: yes
          mem.hotadd: yes
        vm_nic:
          nic1:
            type: vmxnet3
            network: VM Network
            network_type: standard
        vm_hardware:
          memory_mb: "1024"
          num_cpus: "1"
          osid: RH7
          scsi: paravirtual
        vm_disk:
           disk1:
               size_gb: 31
               type: thin
               datastore: VM-Datastore-1
           disk2:
               size_gb: 10
               type: thin
               datastore: VM-Datastore-1