I've talked before about how boxed text, or read-aloud text, is the most direct way an adventure author speaks to the players. This kind of text is great for setting a scene, relaying critical mission information, or focusing player attention on specific elements. However, there are a several things good boxed text shouldn't include. Here are my rules for what you shouldn't say in your boxed text.

* It shouldn't mention creatures. Your boxed text shouldn't say things like "..and then four orcs rush at you!" The text ought to be useful even if the PCs come back to this room later, or if they lured the orcs out in the first place, if they snuck in while invisible, or any number of other variations. The boxed text should be an area description, not a monster description. One caveat: you can describe creatures that are pretending to be features of the room, such as by stating a room has 8 carved columns when 4 of those are actually stone golems that animate to attack when the PCs get close. That emphasizes that the creatures appear as the room features, which is important for those types of monsters.

* It shouldn't assume entry direction. Even though an adventure author has a really good idea about which way the party is going to enter a room, the description shouldn't assume any particular entry direction. Phrases like "the stairs descend before you to a wide hall with four stone doors leading out of it" are bad. What happens if the party came around and entered the room for the first time through one of those stone doors? Sure, maybe those doors are hard to get to without passing through the hall, but in a game where people can teleport or walk through walls, that's not an impossibility. Furthermore, your description should still be useful if a player casts a spell like clairvoyance that lets them look into a room without actually physically entering it from any direction at all.

* It shouldn't assume the players' light levels. Exterior encounters shouldn't assume that it's day or night; adventurers are active around the clock, and sometimes at some pretty weird hours. You can bend this a bit if reasonable circumstance demands it (such as if the party meets a noble for breakfast and is jumped by assassins right as they leave the noble's manor afterwards; sure, it's definitely daytime then). But some groups may travel late, push through the night, or get up early, especially if they feel time pressure. So your exterior encounters probably shouldn't assume day or night light levels. But even interior room descriptions should avoid this. Phrases like "the coins glitter in the reflection of your light," or "your light extends only partway across the cavern," assume a lot about the size of the players' light sources, and that they even have them at all. What if the players cast their most powerful, long-range light spells just beforehand? Or what if it's a party of dwarves and half-orcs who can all see in the dark and don't use light at all? Avoid assuming any light sources that aren't present in the room. If you really want to describe glittering treasure, put a flickering torch in the room to provide the light for it instead. 

* It shouldn't include the word "you." One word to make sure you never (or almost never) use in boxed text is the word "you." You shouldn't say thinks like "the bridge stretches across the chasm before you," but instead just "the bridge stretches across the chasm." "High above you" should just be "high above," or reworded entirely. The only place where "you" is acceptable is in boxed text that includes dialogue, like this: "The pirate king squints blearily and mutters, 'You don't look like the right kinda people for me job. Aren't you just landlubbers?'"

* It shouldn't assume character actions. Avoid text that assumes a character is opening a chest, just barely peeking over an obstacle, or similar. The players have exceptionally broad choice in what their characters do; that's why they're playing an RPG, after all. Narrowing those choices through textual assumptions isn't helpful. Perhaps they summoned a monster to open the chest, or they just decided to climb over the obstacle without looking first.  

* In short, it's short. I've just given you a lot of stuff you shouldn't include in boxed text. Once you've taken all that out of what you wanted to write, you'll barely have any text left at all--just a neutral description of the area. Correct! And that's the kind of boxed text you should aim for. Remember, boxed text isn't the encounter; it's how the encounter begins. It merely sets the stage for all the awesome stuff to happen with creatures and traps and glittering treasure and all that excitement.