The following paragraphs are taken from the Good Councillor's Guide:
At least three clear days before each council, committee or sub-committee meeting, you should be sent a summons and agenda. The three clear days is established in law because it is important to be notified of issues to be discussed. Topics requiring a decision cannot be added to the agenda after the deadline has passed; they must wait for another meeting.
Each agenda item should make it very clear what you as a councillor are expected to do and be precise about the
subject under discussion. For example, an agenda item saying “footpaths” gives you no idea what to expect. It is
more helpful to know that your task at the meeting is
"To receive a report from Cllr Gorie on the condition of footpaths in the parish and to agree action in response to proposals for repairs (copy of report attached)."
It is actually unlawful to make a decision, especially a decision to spend money, without sufficient (three clear
days) warning. Vague agenda items that don’t specify exact business (such as Matters Arising, and Any Other
Business) are dangerous and should be avoided, because the council cannot make unexpected decisions.