OPEC MEETS on Tuesday to raise oil prices again. On Thursday, the heads of seven major industrial nations meet in Tokyo to decide what to do about it. When President Carter sits down with his counterparts from Western Europe, Canada and Japan, the challenge will be clear enough: Tight supplies and frantic demand are pulling against each other worldwide to send prices shooting upward. What's the response going to be?

Their answer will have to meet three tests. It will have to have an immediate effect. It will have to demonstrate a firm resolve for the years ahead; it's got to be more than another attempt at patching along for a few months in vague hopes that something will turn up. Above all, the seven's answer will have to be firm and specific.

For the immediate future, the seven are going to have to cut back on oil consumption. Nothing else holds any hope of stabilizing prices or protecting these nations from every kind of political blackmail by oil exporters. Those cutbacks in imported oil won't have to be big, but they will have to be real and visible. They will have to create what you might call a small glut. Over the past six months, the seven industrial nations have been elbowing and gouging each other in a wild scramble to grab from each other every last pint of oil that anyone has put up for sale anywhere. It is the buyers as much as the sellers who are responsible for the dismaying pattern of price increases since December. That pattern has now become self-perpetuating, and the increases are accelerating. The only way to interrupt them is a firm alliance among the seven at Tokyo to accept the self-imposed discipline of limiting the amounts of oil they use.

Holding down demand will be very effective, temporarily. To make it clear that their purposes are more than temporary, the seven will also have to agree to increase their own energy supplies at home. Without a serious commitment to do more with their own resources, the seven would inevitably slide back into greater dependence on oil from abroad.

To do these things will place terrible political burdens on all of the seven governments. Mr. Carter will have to explain to American motorists, as they sit in gasoline lines, that the country has to forgo those extra few shiploads of oil that, by bidding up the price, it might snatch away from German or Japanese or French consumers. As American householders watch the price of heating oil climb, Mr. Carter is going to have to persuade them that a few shiploads of oil are just going to have sit in the sellers' tanks, somewhere across the sea, to let them know that it's no longer entirely a sellers' market. The United States has given the rest of the world a strong impression that it is desperate for oil at any price, and that its voters won't tolerate any shortage. That's a dangerous impression to leave. Mr. Carter's job at Toyko is to demonstrate that the United States will act firmly to protect the real interest of its allies, and of American consumers.