I’ve updated my article on posting to Mastodon through #IFTTT to clarify that ‘status=’ is a required part of the body, and took the opportunity to verify that IFTTT can handle additional parameters like spoiler_text=___ for CWs, visibility=___ to set unlisted, etc.
You can chain them like this:
spoiler_text=Link: <<<{{Title}}>>>&visibility=unlisted&status=<<<{{Url}}>>> <<<{{Excerpt}}>>>