It appears the Redash slackbot no longer parses URLs, as shown on the Slack Redash bot successful install page. One of the examples there is pasting in a URL, like
https://redash.mycompany.com/queries/3#3 and having it post the appropriate results.
Here’s what you see at https://redash.io/slack
This no longer works. The
/redash commands appear to work.