Top presidential aides were out and about on Washington's party circuit last night, and all in all they were pretty happy about their boss' press conference yesterday.

"I think it went very well," said White House chief of staff James Baker at a book party for Robert Moss' "Death Beam." When asked if Reagan really "had no answer" about whether a nuclear "demonstration shot" is part of NATO strategy, Baker said, "He was not sure that he should be talking about NATO's contingency plans. He knew the answer and was expecting the question."

"He was slow and precise and deliberate -- to be accurate," said national security adviser Richard Allen, when asked if he thought Reagan stumbled over questions about nuclear weaponry. "He wasn't trying to suit the press' convenience."

Last night writer Arnaud de Borchgrave hosted a party for Moss, with whom he co-authored the best-selling book, "The Spike," to promote Moss' new book, an espionage thriller about weaponry in Russia. Morgan Mason, special assistant to the president for political affairs, put it best in describing why so many Republicans were there: "Arnaud and Robert are good guys, and they're known to be on our side, so to speak. They are philosophically attuned to the administration, and we want to embrace them."

"The host is a good conservative," said Baker. "Don't write that. All right, you can write that. The host is a good conservative."

When a good conservative hosts a party these days, a lot of the right kind of people are willing to sandwich into de Borchgrave's apartment. Two hundred people showed up. Getting your hand to your mouth to sip a drink was a challenge. Getting to the bar was unheard of. There was presidential counselor Ed Meese, CIA director William Casey, Republican direct-mail czar Richard Viguerie and International Communication Agency director Charles Wick.

"I'm in the book, you know," joked Richard Allen. "The character of Trip Gage is really me."

"Trip Gage is sort of a wimp in the book," explained the author. "Dick's been concerned that it was modeled after him."

Was it?

"Oh, no, no. Compared to Dick Allen, Trip Gage is really a wimp. It is not Dick."

Life being stranger than fiction ofttimes, Moss offered that "Death Beam's" assessment of the CIA is right on target. "Their international intelligence-gathering is faulty. My stories are based are real events. The bottom line is that our government has not gotten accurate intelligence information about Russia. Ask Bill Casey if I'm right."

Bill Casey, across the room: "I don't read books. I don't know what he's talking about."

In addition to this year's familiar party faces were one or two from yesteryear. Like socialite Page Lee Hufty Griswold. "I'm just a housewife now," said Washington's once-most-popular bacheloress. "I live on a farm, do some work with the Baltimore Museum of Art and play with my son. The limelight was fun while it lasted, but I don't miss it."

And like Jimmy Carter's national security adviser, Zbigniew Brzezinski. "No, I wouldn't say the administration's foreign policy is in disarray," he said. "I'll tell you why. You first have to have a foreign policy before it can be in disarray."