Channel, private group, or IM channel to send message to. Can be an encoded ID, or a name.
Content
The text to send. Whether the parameter is required depends on your usage of the Blocks & Attachments parameters. For more information see Slack documentation.
User
The ID of the user who will receive the ephemeral message. The user should be in the channel specified by the channel parameter.
A JSON-based array of structured attachments, presented as a URL-encoded string.
Blocks
A JSON-based array of structured blocks, presented as a URL-encoded string.
Parse
Change how messages are treated. Defaults to none. For more information see Slack documentation for more detail.
Thread Timestamp
Provide another message’s Timestamp value to post this message in a thread. You can obtain a message’s Timestamp by using the Get Channel Message's action. Avoid using a reply’s Timestamp value; use its parent’s value instead. Ephemeral messages in threads are only shown if there is already an active thread.