Yeah I got bit by that too, once. But it makes sense. If everything is a command, then "#" must also be a command. Essentially like a NOOP.

Once I visualized it that way, I never got tripped up by that again.

And regardless of this fact, comments exist. They may not be as convenient as using // or // in C its friends, but they exist. To say that tcl does not allow one to know what a complicated line of code means is absurd.