President Reagan has quietly designated Vice President George Bush to be his personal coordinator of the Economic Summit at the Chateau Montebello in Ottawa July 19 and 20. This, the White House tells me, signifies that the president seeks to assure his team at Ottawa will speak with one voice.

But even more important, the president has privately passed the word that summit meetings should focus more on general, long-term strategy, and less on specific decisions that preoccupied presidents Ford and Carter at the six earlier sessions.

If Reagan has his way, Ottawa may turn out to be the most broadly based of all the summits so far, going well beyond economic problems into the strategic puzzles confronting the big Western democracies. There will be no "political" agenda as such, but the summit will touch on the Soviet-Afghanistan question, arms control and Poland, among other issues.

It also is sure to be one of the more interesting gatherings of an always ego-overloaded meeting. New to summitry will be President Reagan himself, French President Mitterrand, Japanese Prime Minister Suzuki and Premier Forlani of Italy. Only Canadian Prime Minister Trudeau, British Prime Minister Thatcher and West German Chancellor Schmidt are summit veterans.

Mitterrand's opportunity in this setting to elaborate specifics of his Socialist program for France is alone worth the price of admission. While Reagan is sure to tout the benefits of his free-market, supply-side approach, Mitterrand is likely to go the opposite route, arguing or beefing up old-style demand stimulants so as to reduce unemployment in Europe.

Increasing emphasis on issues with political overtones would continue a trend already under way. Recent summits, in addition to the standard economic, energy and trade issues, broadened out to include problems such as hijacking, international refugees, terrorism -- and last year at Venice, how to respond to the Soviet invasion of Afghanistan.

As a transition paper prepared at the State Department after Reagan's election observed, "Economic issues are increasingly the stuff of foreign and security policy." The greater the identity between foreign economic considerations, and foreign policy itself, the more political summits are likely to become.

An even bolder approach was suggested in a recent paper presented to the Trilateral Commission in Washington by Miriam Camps, a senior fellow of the Council on Foreign Relations. Camps argued that much of the economic discussions scheduled for "crisis-oriented" summits should be transferred to a strengthened International Monetary Fund and to a brand-new global trade organization, making the main focus of the summits more political.

Although many of the European nations are quite willing to make these sessions "macro-political" as well as macro-economic, they are less sure about any system that would sidestep some of the nitty-gritty economic issues. They suspect that part of Reagan's effort to reshape summits resides in an ideology unfavorable to the Third World. Trudeau, for example, fears he may not get the detailed discussion of North-South issues he had earlier planned.

A report on rich-world, poor-world relations had been commissioned last year at the Venice summit for discussion at Ottawa. But while Reagan is taking an active role with President Lopez Portillo in the development of the North-South summit in Mexico scheduled for October, he wants the Ottawa summit to pay less attention to North-South issues, and more to East-West issues. At this juncture, a White House that views the Soviets as an increasing threat considers the East-West problem of overriding importance.

Just last week at the International Monetary Fund-World Bank meeting in Libreville, Gabon, President Reagan's men signaled that his administration will be sticky in approving an expansion of government aid for the Third World. The Reagan administration wants the Third World to try out "supply-side" eperiments that will create a better environment for private capital investment.

The real question lying ahead for economic summitry is how far the leaders are prepared to go in handling off to lesser agencies some of the "messy details" -- such as protectionist tactics, development aid or how best to encourage exploration for oil in the Third World.

At the moment, Miriam Camps is probably too far ahead of the game. The multilateral agencies aren't equipped to make such key decisions by themselves, and the Reagan administration, suspicious of the multilateral approach, obviously is not going to enhance their clout.

The State Department excepted, the Reagan administration thinks that the multilateral agencies, especially the World Bank, do not well serve American strategic and security interests abroad. So, if there is to be any coordinated approach to the world's pressing macro-economic problems, summitry should continue as the vehicle to galvanize individual countries into action.