Now that you mention it, this is one of my pet peeves as well.
In the specific case of XCF, I will usually just check the rulesets (or the ruleset-based interface at xcf.trigramreactor.net) for potential restrictions on all the special missions. In XCF this is far from obvious (for example, some undercover missions allow a helicopter while a few do not - not sure if this is intentional; 'slander' missions intentionally allow you to use just the slowest possible transports to never get there in time).
Looking for this information outside the game works for me (at least for this mod that has such an easy interface), but I'd certainly vote for a real game GUI to display this if it can be easily accomplished to make this much easier for everyone.
By the way, if this is improved, I why not also show 'Forbidden soldier types' and 'Allowed item categories' strings on this screen (whether all of them or just the ones researched). You could just show all the 'Allowed crafts' strings, or just those that you have researched at this point (like in the popup now).
