Add Request API problem

Hi, i'm trying to create "tickets" using the add request module

https://www.manageengine.com/products/service-desk/sdpod-v3-api/requests/request.html#add-request

When i execute my script using this payload

payload = {
      "input_data":{
              "request": {
              "subject": "This is a api add request test",
              "description": "Api Test"
              }
       }
}

I'm receiving the message

"{'response_status': {'status_code': 4000, 'messages': [{'status_code': 4001, 'field': 'input_data', 'type': 'failed', 'message': 'Unable to parse the JSON'}], 'status': 'failed'}}"

When i try to follow to pass this information as a string

payload = """input_data={"request":{"subject":"This is a api add request test,"description":"Api test"}}"""

i receive:

{'response_status': {'status_code': 4000, 'messages': [{'status_code': 4001, 'field': 'input_data', 'type': 'failed', 'message': 'Value not provided'}], 'status': 'failed'}}

The headers i'm using:
Accept: application/vnd.manageengine.sdp.v3+json

Content-Type: application/x-www-form-urlencoded

technician_key: XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX

Someone can help me?