curl --request POST \
  --url https://api.zapier.com/v2/actions/{action_id}/inputs \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "data": {
    "authentication": "928117",
    "inputs": {
      "spreadsheet": "my_sheet"
    }
  }
}
'

{
  "links": {
    "next": null,
    "prev": null
  },
  "meta": {
    "count": 2,
    "limit": null,
    "offset": 0
  },
  "data": [
    {
      "type": "input_field",
      "id": "input",
      "default_value": "",
      "depends_on": [],
      "description": "Use the Input Data fields above to assign key names (left) and map values (right) from previous steps. Use notation `inputData.keyName` or `inputData['keyName']` to access the values within your code. The data will be provided **as strings**. Learn more [here](https://zapier.com/help/create/code-webhooks/use-javascript-code-in-zaps#input-data-for-code-steps).",
      "invalidates_input_fields": false,
      "is_required": false,
      "placeholder": "",
      "title": "Input Data",
      "value_type": "OBJECT"
    },
    {
      "type": "input_field",
      "id": "code",
      "default_value": "// this is wrapped in an `async` function\n// you can use await throughout the function\n\noutput = [{id: 123, hello: \"world\"}];",
      "depends_on": [],
      "description": "**Warning! This is an advanced action!** Uses Node 10.x.x. Please read the [Code documentation for more information](/help/create/code-webhooks/use-javascript-code-in-zaps).",
      "format": "CODE",
      "invalidates_input_fields": false,
      "is_required": true,
      "placeholder": "",
      "title": "Code",
      "value_type": "STRING"
    }
  ]
}