How To provoke AI

[The Despondent Mind]

I want to provoke my neighbor to attack me

I hope the solution is universal for all mods .

[Aymer de Valence]

Keep demanding huge sums of money off of them. They gradually get angrier and angrier. This could lead them to attacking you. Also, deliberately leave a border region lightly garrisoned. The AI loves it when the player does that. "easy pickings"

[Drachos]

Order your armies to march through their lands, you'll get a "sliding" notification on the left side which says: "Relations worsened" or something like that.

[Surgeon]

Disbanding some of your troops should lower your military ranking and make you seem like an easier target, too.