Telling someone to ask/demand an action “Ask your … to …”

Question

For a couple of days now I have been using the application tandem that let you speak with a native speaker of a language that your are learning. The idea is that the person will help you with X while you help him with Y.

Yesterday my Japanese teacher told me that I should ask my partner to correct all my mistakes (and not leave some for the sake of politeness).

So now I want to write to that person ： "My teacher said [You need to ask your partner to correct all your mistakes]".

I am having issue translating the part where I quote my teacher.

私の先生は「あなたはあなたのパートナーにあなたの間違いを訂正して欲しいが必要です」といいました。

I came up with this. I didn't found a way to say "ask him to do it" but I found people using 欲しい instead.

I also found this post here that tells to use 必要です for something really necessary when I use "need to/have to". But is　「必要です」 too strong a word ?

So that's my best guess but I'm pretty new to japanese.

Answer 1

First, here is a translation of your sentence to help you understand.

私の先生は「あなたはあなたのパートナーにあなたの間違いを訂正して欲しいが必要です」といいました。
My teacher said "You, by your partner, want to fix your error is needed"

The first あなた is redundant.

The following :

訂正して欲しい : wants someone to fix
が必要です : is needed

Would make more sense this way :

訂正してもらう : to receive someone's correction
必要があります/ことが必要 : there is a need to / is needed

欲しい is a desire, and saying that your desire is needed does not make much sense. Also note that saying that it is needed for your partner to fix your mistakes seems a bit over the top. Unless your partner has a contract and is getting paid by your teacher. It might be better to say something like "if possible, it would be best if ...". Which can be said in the following way.

出来れば、訂正してもらった方がいいです。

So in the end you would get something like this.

私の先生は「（出来れば）あなたのパートナーにあなたの間違いを訂正してもらった方がいいです」といいました。