"The description by my friend was too short."
Translation:La priskribo fare de mia amiko estis tro mallonga.
That sounds like "the description according to my friend" rather than "(written) by him" to me.
You could use de, though then it would be ambiguous whether the description described your friend or whether it had been created by your friend.
Yes; it neither comes out of your friend nor is it made out of your friend (i.e. using your friend as ingredients or raw materials).
el is basically "(from) out of".
I want to chime in and support Mizinamo's answer here. It seems the confusion is with the English word "from" and not with the definition of "el" and "de".
I don't think people conceive of descriptions as things which exist inside people and then come out of them. The counter examples of gifts being in one person's hands and then coming out of those hands make sense on their own, but do nothing to illustrate a description belonging to (being made by) someone.
Perhaps the contradiction is a cultural one based on different perspectives - the occidental and the oriental. The one perceives existence as concrete whilst the other perceives it as abstract. The latter makes little distinction as to whether the source is concrete (hands) or abstract (mind).
Possibly, but I'm not convinced yet. First, in two decades of speaking Esperanto, I have not gotten to know anybody who says "priskribo el mia amiko." Second, while you've come up with a few examples of "el" in use, none of them are related to "priskribo." If you want to speak Esperanto the way Esperanto speakers speak it, you'll say "priskribo fare de mia amiko" or similar.
There are many published examples such as "... ricevis donacon el la manoj de ..." which contradict your comment.
I would understand that as "from out of your hands" -- treating "your (cupped) hands" as forming a space out of which something can come.
Even in English we talk about something being "out of my hands" (no longer in my power) with "out of", though we don't say that "I got a present out of my friend".
... an example from http://esperanto.china.org.cn/2016-05/11/content_38430777.htm:
La brita ĵurnalo Daily Mail raportis, ke Julian Assange, la fondinto de Vikiliko, ricevis dumonatan katon kiel donacon el sia infano.
This usage strikes me as odd. It appears to be from El Popola Cxinio - and I would hesitate to call it a model sentence. You'd be hard pressed to find a similar example from Monato or the Fundamento.
In any event, receiving a gift from inside your child is not the same as receiving a description from inside your friend. Please see my other reply in this thread.