Opening the book…
Half of the friction on a team is unfinished conversations: the question nobody answered, the request that vanished into a channel, the 'I'll look into it' that never came back. Each open loop is a small tax on someone's attention, because they have to keep remembering to check whether the thing happened. Closing the loop, replying even just to say 'done' or 'no, and here's why,' is what turns a pile of messages into a system people can trust. When loops reliably close, you can fire off a request and stop carrying it, confident it'll come back. When they don't, everyone hedges by following up, nagging, and holding mental state they shouldn't have to, and the whole team runs slower and more anxiously. It's a small courtesy that, done consistently, is indistinguishable from reliability.
When someone asks you something, answer it, even if the answer is 'not now' or 'I don't know, ask X.' When you say you'll do a thing, come back and confirm when it's done, or say if it isn't. If you pick up a request from a channel, react or reply so the asker knows it's owned and can let it go. When a decision or discussion wraps, post the outcome so the people who were following don't have to wonder. Don't leave direct questions on read; a one-word reply beats silence every time. And if you're going to be slow, say 'I'll get to this Thursday' so the other person can plan around your latency instead of guessing at it.
Not every message needs a reply; a broadcast FYI or a thread that's clearly resolved doesn't need an acknowledgment from everyone. Use judgment about what's an actual open loop versus ambient chatter, and don't manufacture ceremony where none is needed.