Ragnarok is providing it and pretty much everything related to the world, like new rooms descriptions through discord. Although we read them in discord, so far we've been posting them here so the thread makes sense. The last one just happens to be in Robin's posts because she's scout-like and nosy, making her often one of the first to step into into a room. You might have noticed other characters noticing things about a room or finding loot after it's first described — that's because they got better Perception rolls or performed a more through search.
We have most autonomy over each of our characters (looks, background, reactions) and over descriptions of attacks and how successes and failures happen (eg character X missed because they weren't used to a specific gun). Critical success/failure descriptions such as Jay's unbelievable wrench throwing are courtesy of Ragnarok.
This is the first play by post I'm in that uses a forum + discord combo. Usually you keep an OOC thread for technical discussions in addition to the game thread, with confidential descriptions done through PMs. I like the combo so far, discord channels help to keep things organized. The only risk is forgetting to post the in-game info we got there. I guess the other downside is keeping it a bit more opaque for people following the game, as they didn't get to see backgrounds, sheets or character art.
(Hah, I got ninja'd by Grey)