Currently what is on my mind is 2 methods:
1) Go to the slash command app webpage and scrape the HTML
2) Use one of the slack API commands to query for it
Currently where I am stuck:
1) The HTML codes produced when I am logged on using Chrome vs when I authenticate using tester token via Python is different. Hence, when I use Python (requests and lxml libraries), the resulting HTML codes do not contain the slash command details.
2) I have navigated through the Slack API commands, but it mostly revolves around sending messages, bots, etc. I couldn't find an API command that is able to retrieve the slash commands list and the details (e.g. description, permissions, etc.)
We have now found an undocumented API method that returns the list of all slash commands (build-in and custom) from a workspace.
Syntax: https://slack.com/api/commands.list?token=YOUR-TOKEN
Note that you need a legacy token for this method to work.
You can find a full documentation of this method here.