When creating a meeting, include the agenda as a question or questions that need to be answered.
For the meeting creator, this approach compels them to consider the purpose of the meeting, enabling them to better judge who should attend and how long the meeting should last. Or even if the meeting should occur at all. maybe an email will suffice.
Questions provide the attendees with a better opportunity to prepare for the meeting by contemplating the answers beforehand.
When attending the meeting, you then have a more constructive agenda. This should make it easier to bypass the small talk and jump right in.
Once the questions are answered, you know the meeting has concluded.