[The Glyphstone]

Like Gavinfoxx says, it's highly dependent on the Lord in question, and his Dynasty - the various Lords of a Dynasty will have similar behavioral attitudes and outlooks (even if they are degraded to varying degrees) to each other and to the Phaeron of their Crown World. The more isolationist/xenophobic this particular Lord is, the less he'll be willing to tell the Culture about his intentions for fear they'll try to stop him for some reason. The more ambitious he is, the less he'll say for fear one of his underlings or rivals will take advantage of something they overhear.