FYI - For Your Information.
I regularly answer to a #toot with just a bunch of #hashtags related to the content or media of the said #post.
It's not only a matter of search engine optimization (#SEO), but also a stake of #findability for this #content.
If search engines (#DuckDuckGo, #Kagi, #SearxNG...) may index your #Mastodon account, according to you settings,
the software itself does not index a toot unless it has a #hashTag.