You may be needed for one item in a longer meeting. Agreeing to attend “for a few minutes” leaves both you and the organiser uncertain about when your contribution will happen.
Confirm the item, approximate time window and what the group needs from you. Are you presenting a result, answering questions or participating in a decision? Ask how you will be told if the agenda moves ahead or falls behind.
An illustrative arrangement is: “I can join for the accessibility review. Please message me when the preceding item starts; the written findings are already available.” Use whatever contact method is appropriate for the team.
Leave the contribution usable
If you must leave before the discussion ends, identify where your supporting material is stored and who can clarify factual details. Do not imply that somebody else can approve changes on your behalf unless that authority has actually been agreed.
Ask for the decision or action affecting your work afterwards. Attendance at one segment does not guarantee that you heard a later revision.
For the organiser, put the guest item visibly in the agenda and avoid making the person wait through unrelated discussion without an update. Partial attendance works when the boundaries are explicit enough that everyone can prepare and the meeting can continue smoothly after the guest leaves.
Editorial illustration from this site’s image library; not documentary evidence of the example or object discussed.