Writing NPCs
When writing NPCs, you can communicate 2 or 3 things, or 4 related things. Anything more than that, and you’re either going to be ignored by the person running the game, they’re going to change it, as is the nature of translation, or they’ll be checking your notes so often that they do a worse job of running the game than if they’d just winged it.
That said, NPCs changing when used in play isn’t a bad thing - it just means you can’t rely on things being true about them any more. Experience reproduction is something I’m actively against in RPGs: this is more about using your various pieces effectively.
I’ve been running Classic Traveller Adventure 08, Prison Planet, which has a shitload of NPCS and communicates them super effectively: the other trick it uses is the UPP, which encodes some general info into the stats and skill. The order for the stats is Strength Dexterity Endurance Intelligence Education and Social Standing, using hexadecimal notation (e.g. A=10, B=11 etc.) Below is an page of NPC stats. Personally I’d use a name to refer to the rumours so I can immediately tell which rumour it’s in reference to, but otherwise this is great - gives you plenty to riff on, doesn’t take ages describing the character, and doesn’t set up stuff to get ‘wrong’.