It's not mandatory, but it sure is helpful. Common and Latin names, germination
and growing information, type of plant (annual, biennial, perennial), and the date of seed collection can all be very useful
information for the receiver. In lieu of writing all this out on the packets, you could send an URL if you can find the necessary
information online, but at minimum label each packet with the name of the seeds being sent and from whom.
If you are not absolutely certain of the exact identity of the seeds you are trading, tell the other
trader so. Mistakes and disappointments can be kept to a minimum when such communications are made openly and honestly.