Pick one recurring breakdown
Ask each person to recall a moment in the last two weeks when expectations diverged. One person may have treated a request as urgent while the other expected to answer by Friday. Note what people did at the time and what signal they needed. One episode that several people recognise is enough to draft the first agreement.
Write down the action, channel, and timing
For example, when another department’s work is blocked, the requester posts in the project channel with the obstacle, the action they need, and the deadline. The person on duty replies within two working hours. If the obstacle remains at the deadline, they raise it with the project lead.
Put the agreement where the work happens
Place the agreement where people make the request. Two weeks later, look at the actual messages and adjust the wording. If people keep picking the wrong channel, link to the right one. If the response deadline is consistently missed, check who can cover for the person on duty.