In return for a full peace agreement with Egypt Israeli Prime Minister Menachem Begin has conditionally agreed to withdraw roughly half of the Israeli troops now stationed on the West Bank territory of the Jordan River, U.S. officials disclosed yesterday.

But the text of the two "framework" agreements signed by Begin and Egyptian President Anwar Sadat Sunday night and released yesterday show that Begin has been able to do this while keeping alive Israel's determination to resist a total withdrawal from the West Bank.

Release of the framework documents was accompanied here by briefings from senior U.S. officials who refused to be identified. They sought to amplify on President Carter's assertions that the agreements reached at the Camp David summit represented a major step forward for chances of a lasting peace in the Middle East.

Divided into sections on an Egyptian-Israeli peace treaty and a more comprehensive framework of principles for a peace that would cover the West Bank and Gaza, the accords in fact encompass three separate areas - agreement between the two countries, a series of artful evasions on unresolved points, and outright disagreement.

Most of the agreement is on the Sinai peninsula, which goes back to Egypt within three years if Sadat will sign a full peace treaty establishing normal relations with Israel and opening the Suez Canal to the flow of goods, presumably including military supplies, to Israel. Sadat has agreed to sharply limit the number of troops he will station in the Sinai when he gets it back, and he is willing to establish demilitarized buffer zones near Israel and the strategic Sharm el Sheikh coastal headland that will be manned by United Nations peacekeeping forces.

To secure Israel's agreement to hand over three airfields it has controlled in Sinai, the United States agreed to build for Israel two military airbases just inside the Sinai frontier before the three-year phased pullout of Israeli troops is completed, U.S. officials said yesterday.

The U.S. commitment is not contained in the formal agreement, but is to be covered in what officials called "side letters" the three delegations are due to exchange in the next day or two. Senior U.S. officials said the air base commitment was the only U.S. undertaking given to either side to make the agreements possible.

The three delegations will also exchange letters on the subject that provoked open disagreement, the status of East Jerusalem. They will merely restate the Egyptian position that East Jerusalem should not be left underiIsraeli jurisdiction, the Israeli assertion that it will never give up any part of the city, and the more equivocal U.S. objection to Israeli annexation of the city. It's status remains to be decided.

"The two sides clearly agreed to disagree," one U.S. official said of the arrangement on the previously Jordanian-held section of Jerusalem. Begin made explicit in television interviews last night that "the position of Israel is not going to be changed" under any circumstances."

The ambiguities in the agreements largely surround the West Bank, the territory inhabited by 1.1 million Arabs and ruled by Jordan until 1967, when the Israelis took the Sinai, the West Bank and Gaza Strip and Syria's Golan Heights during the Six-Day War. Begin again referred to the territory last night as "Judea and Samaria," the Biblical names for the district, which Begin until recently had said he would never give up.

The accords provide for a five-year, three-stage set of negotiations over the West Bank and the Gaza Strip that are intended to resolve "the final status" of those two territories. Sovereignty and keeping Israeli troops on the West Bank past the five-year period are questions deliberately left open.

In television interviews last night, Begin dispelled some of the artful evasiveness that 23 drafting sessions all carried out by the U.S. delegation at the Camp David summit, had care fully sought to instill in the 12-page framework agreements.

Begin said Israel would assert its claim to sovereignty over the West Bank in the negotiations on the fate of that territory. He also said that, under his interpretation, the agreement has been written in a way that gives Israel the right to keep troops on the West Bank indefinitely.

From the two official documents, the U.S. briefings and Begin's remarks to Israeli radio, it emerged that he had given Sadat much less than other U.S. officials had indicated to reporters on Sunday night immediately before the signing ceremony.

While it had appeared earlier that Begin would commit Israel to suspending establishment of civilian Jewish settlements on the West Bank throughout the five-year negotiations it became clear yesterday that he has given agreement only to suspend new settlements on the West Bank for the period of negotiations leading to elections for a "self-governing" authority composed of local Palestinians.

U.S. officials estimated this period as perhaps as short as three months. Their remarks, however, left the clear impression that if the West Bank arrangements were proceeding smoothly, the United States would use its influence to try to prevent Israel from threatening them by starting new settlements.

It also emerged yesterday that, contrary to an impression given by a senior U.S. official Sunday night, no United Nations peacekeeping forces or other foreign military units would be stationed on the West Bank to replace the Israeli troops that are due to be pulled back into Israel as a result of this accord.

Cautioning that Israel had not given a specific commitment on numbers, administration officials said that the idea of cutting the 11,000 troops now thought to be stationed on the West Bank down to about 6,000 had been discussed during the 13-day secret talks at Camp David.

The troops remaining will be pulled fied locations. But they will continue to be responsible for the most important aspects of security on the West Bank during the entire five-year negotiating period, and can be sent back in by Israeli government - to augment the local police force that is to be formed - if trouble develops in the cities.

Begin is promising under the framework agreement to give "full autonomy" to the West Bank and Gaza inhabitants. Sadat obtained several compromises on semantics as Begin signed the document that calls on Egypt, Israel, Jordan and "the representatives of the Palestinian people" to negotiate "on the resolution of the Palestinian problem in all its aspects."

The negotiations, to be based on United Nations Security Council Resolution 242, "must also recognize the legitimate rights of the Palestinian people and their just requirements," the document states.

This has been a code phrase for political leadership popularized by the Palestine Liberation Organization. But under the complex negotiating arrangements, Israel maintains a veto right over participation in the negotiations by the PLO leadership, which is based outside the West Bank and Gaza.

In the first negotiations to set up election machinery for the self-governing authority. Egypt and Jordan may name Palestinians to their delegations. If they currently reside on the West Bank or in Gaza, they can join the delegations no matter what their political views are, U.S. officials said.

But naming Palestinians who live outside those territories to the Egyptian and Jordanian delegations has to be agreed to by Israel, under the terms of the agreement.

On security, the agreement calls for "all necessary measures to be taken" to assure "the security of Israel and its neighbors during the transitional period and beyond." Begin asserts that including the word "beyond" means that Israel will have the automatic right to keep troops on the West Bank if needed past the five-year interim period.