The UpdatePostMessageSlackAction datatype includes various settings.

Table: UpdatePostMessageSlackAction

viewNamestringyes The name of the view of the action.
idstringyes The unique identifier of the action.
namestringyes The name of the action.
apiTokenstringyes The API token to authenticate with Slack.
channels[string]yes The list of Slack channels to message.
fields[SlackFieldEntryInput]yes Fields to include within the Slack message. It can be templated with values from the result. See SlackFieldEntryInput Table.
useProxybooleanyes Defines whether the action should use the configured proxy to make web requests.

[a] Some arguments may be required, as indicated in this column. For some fields, this column indicates that a result will always be returned for it.