Do I need a chain tool for a Shimano HG-73? I didn't think so, since there is what appears to be a "quick link." But upon doing what I normally do with SRAM and KMC quick links, the chain was not off. So I went and checked out The Internets, which told me that I need a chain tool for this particular chain. So I went to my LBS for a chain tool. The mechanic told me that I didn't need one (but I'm not really sure about this, since my Korean isn't very good and he just pointed at the "quick link" and motioned a little bit).

So what's the deal? Do I need a chain tool or not on this chain? It's on a Surly Cross-Check complete if that helps any. And if I do need a chain tool, why is there what looks like a quick link?

To do what. Install it? Uninstall it?

You need a chain tool to at least shorten the chain if you're installing. It's unlikely the default length the chain comes in is the correct length, quick link or not. If you're going to toss the chain just bolt cutter it off. Hg-73's don't come with quicklinks sram or kmc style. They use pins for installation.

Shimano chains do not include a quick link and you must use a chain tool to remove the chain and a specific Shimano replacement pin to install it.

If you have a quick link in your chain, it was installed as a aftermarket part.