* "Attached" needs a noun: "Attached" is an adjective and needs a noun to modify.
* Implied noun: The noun "agenda" is implied, but it's better to be explicit.
Here are some more grammatically correct ways to say it:
* Please see the attached agenda. (Most formal and clear)
* Please find the agenda attached.
* The agenda is attached for your review.
* Attached is the agenda.
Choosing the best option depends on the context and the tone you want to convey.