At some point an agile thing (developer, project, business, whatever really) interfaces with something else. This is hard. Oh and its boring, its boring because you have to keep repeating the same ideas until they stick. And then un-stick them and re-explain because the wrong ideas has suck.
An electronic engineer would call this an impedance miss match.
The standard , solution to this seems to be to preach, oh sorry educate what ever is on the other side of the interface. The essential problem with this is that unless the entire work decided to be agile there will always be an interface. So we need a way to deal with it that doesn't involve conversion.
Oh and to be honest wile we think that its the most important thing in the word, err, no one else gives a damn.
They would mostly just like it to work please, soon if possible.
So how can we avoid going nuts repeating ourselves. Simple, get someone else to do it for you. Absolutely insist that someone from the other side of the interface is involved in the agile thing you are doing.
They can then go and explain what is going on for you, thus preserving your sanity.
Oh and your going to fail if you don't have it.