That's weird, i only have the usual electronic ticket (it does mention the booking class which is Q for AA, and G for Alaska), but no separate "ticket receipt" (or is the same?)
Anyway, not a single word about luggage.
Maybe it's because i booked the ticket on the German version of AA.com...
I got another booking made on the american version of aa.com, and there is indeed the baggage information.

So, you mean Alaska will honor it?
The itinerary is the following:
MEX-PHX-GEG AA/US
GEG-SEA-SFO Alaska