I will be technical.
IMO, bridge rules would not have the 1 - P - 1 as alert or announcement during the bidding, since it is natural and contains at least 4 of the suit. As for an announcements, they should be short and with few words. Examples: transfer, could be short, etc.
Now, the statement should be on your convention card and you should draw the opponents’ attention to your convention card before the round begins.
Jim, we have the WBF to thank for the fact that there are
no laws governing what must be disclosed in the laws of bridge.
How you must disclose, yes, but
what is disclosable is specifically delegated down to the different national organisations, or regulating authorities I believe is the current technically correct term. What you must alert in the USA is very different from what you must alert in the UK, for example. There was a point in the UK when even Stayman was alertable, and also minor openings which could be on only 3 cards.
And as for the (damn silly!) rules which some countries have on disclosure via the convention card, don't even get me started on that! The English Bridge Union card was absolutely geared towards Acol players, and they also had the rule that all disclosure must be on the card, but that no supplementary sheets were allowed! So you were reduced to (as I used to do) blowing up a CC on a photocopier to an enormous size, filling it in with a map pen, and then shrinking it back down again. Was it legible? Well, yes, if you had 20/20 vision, and preferably even better than that. It was
legal, though. No regulations covered the size of your writing.
BBO's rules are simple, you should alert anything that your opponents may not fully understand. My view of that regulation is that if your 1
response to 1
is usually made on a stronger hand than normal, you should alert it. I aim to give full disclosure. I would far rather give opponents information to which they are not strictly entitled than withhold something to which they are entitled.
I don't honestly know what the current ACBL convention card looks like. If you have one filled in for OCP, then please scan it and post it. I would be
genuinely interested to see it.