Compare Two Ways to Decline the Same Meeting Invite, One With a Reason and One Without

You need to decline a meeting invite and cannot decide whether giving a reason makes you look more reasonable or just invites a follow-up question. This drafts both versions, one honest and brief, one polite and unexplained, and tells you the likely social cost of each in a UK workplace before you hit decline.

I need to decline a meeting invite, [describe the meeting and why you want to decline]. Write two versions of the decline message: one that gives a brief, honest reason, and one that declines politely without explaining why. For each version, give me one sentence on the likely social cost or benefit of using it in a UK workplace. Keep both messages under three sentences each.