curl -v -H "Authorization: Bearer <ACCESS_TOKEN>" https://actions.zapier.com/api/v1/dynamic/exposed/
{
  "results": [
    {
      "id": "01GTB1KMX72QTJEXXXXXXXXXX",
      "description": "Slack: Send Channel Message",
      ...
    }
  ]
}

Here’s a basic example of how you can list allowed actions.