Magic links for comments are great
They allow you to very easily write helpful comments, as they allow you to link to each sites most important resources with very short links where you don't need to do a search for individual Hyperlinks before posting a single standard comment.
But many people don't know that they exist
The only problem is that many people are not aware of this feature. Even longterm users of StackExchange often don't know about these useful short links. They are a bit hidden. Specifically you currently have to go to the privilege page for comment everywhere and then click on a small subset of markdown. This is basically the same site you would get when checking out the markdown features through the advanced help when writing an answer or question, just with the expanded features for "Comment formatting" expanded and at the top - which is probably the reason only a few people ever check out this small subset of markdown.
The privilege page for comment everywhere doesn't explicitly mention them
Currently the text in the privilege page only mentions italic, bold and named hyperlinks as examples for the subset. I think it would be useful to say that additionally to the markdown in questions/answers there are magic (or shorthand) links in comments.
This is not a subset of what's available in questions/answer, it's an addition and therefore relevant to explicitly state in the text.
The privilege page for comment everywhere should explicitly mention them
If I know the markdown for questions/answers and someone tells me that comments use a subset then I won't expect additional ways to have shorter links to the most important resources. A simple sentence would be enough, something like:
In addition you can use some shorthand links to refer to important resources on the network, such as
[tour]to refer to the tour.
Maybe the commenting will get better
If it's easier for people to write useful comments that point them towards important resources they might be more inclined to actually refer newer users to these resources. When you are not using magic links you have to search for each link every time if you are not already using some userscripts - but in such cases you likely already know about magic links.
Currently many people don't know about this feature, making it a bit more prominent might help. There will still be many people who don't know about them because they don't carefully read the privilege pages, but maybe it will be useful in some cases and thereby contribute to our efforts to make comments more helpful. This could be especially important for those that are trying to greet new users and those that are participating in the closure/reopening process.
Simple magic link example
A comment such as
Welcome to WorldBuilding! Your question is currently missing a bit of information. Could you  it to include xyz? If you have a moment please take the [tour] and visit the [help/on-topic] to learn more about the site. You already have more than 20 reputation, so you might also be interested in checking out [meta] where we discuss how the site should work or visit the [chat] for some more open-ended discussions. Have fun!
would be expanded to say
Welcome to WorldBuilding! Your question is currently missing a bit of information. Could you edit it to include xyz? If you have a moment please take the tour and visit the help center to learn more about the site. You already have more than 20 reputation, so you might also be interested in checking out Worldbuilding Meta where we discuss how the site should work or visit the Worldbuilding Chat for some more open-ended discussions. Have fun!