An update should do something
A project update earns its place when it helps someone act. A long list of completed tasks can look productive while leaving the most useful question unanswered: what does the team need next?
Put the decision first
If a project needs a choice, say so at the top. Explain the options, the tradeoff, and when the choice matters. Link to the supporting work instead of putting every detail into the message.
Name the next step
Be specific about the next action and who owns it. “We are making progress” is pleasant but difficult to use. “The homepage is ready for design review on Tuesday” gives everyone a shared expectation.
Let the board carry the detail
Your project board can hold the task history, dates, and attachments. The update can concentrate on the meaning of those changes. A few clear sentences are usually enough to keep the people around the project informed.