I wonder if there is a rule how to say it right. Let’s say you want trade wood for straw. So you have wood and the other one should have straw. So you ask:
Tauscht jemand Holz gegen Stroh?
But if you swap Holz and Stroh it means the same.
Tauscht jemand Stroh gegen Holz?
So which one should be first: What I have or what I want?
As simple as that:
Ich tausche das, was ich habe, gegen das, was ich will.
You can only tauschen, what you already have. What you get for it, is introduced with the preposition gegen.
My family plays the game die Siedler von Catan a lot, wherein a large part of gameplay centres around people swapping goods. I’ve noted that we hardly ever use the word tauschen for the direct exchange to prevent just that ambiguity. If I have wood and I need grain (it’s not really straw in the game), we usually say:
Will jemand Getreide abgeben?
Will jemand Holz haben?
With these verbs it is always clear which direction you are talking about. We only use tauschen in a very generic way:
Will jemand mit mir tauschen?
Note that contrary to Barth’s answer, I initially understood the sentences in the wrong way, so it is definitely better to prevent any misunderstanding on the word choice level.
