The deal, published by Lebanon's cabinet on Wednesday, runs to just over five pages of printed text and includes a map of southern Lebanon.
The area to be free of Hezbollah weaponry is delineated by a red line labelled "New 2024 line" that runs east-west across Lebanon.
It starts from a point on the coast about 25 km (15 miles) north of the Israeli border and runs eastward, mostly along the Litani River but then diverging from it north of the town of Yohmor, thus going beyond the area that U.N. Security Council Resolution 1701 said would be free of non-state arms.
Resolution 1701 ended the last round of conflict between Hezbollah and Israel in 2006.
The expanded zone includes Beaufort Castle, a Crusader-era fortress considered strategic because it commands a view onto the Israeli border, said retired army brigadier general Hassan Jouni.
The 2006 resolution also said there would be "no weapons without the consent of the Government of Lebanon" deployed across Lebanese territory.
The new ceasefire deal goes further, stipulating that only "official military and security forces" in Lebanon are authorised to carry arms.
It specifically names those forces as the Lebanese Armed Forces, the Internal Security Forces, General Security, State Security, Lebanese customs and municipal police.
"Naturally it means a seriousness with implementation, so that there is no obscurity around this that could be interpreted in a different way," said Jouni.
"It serves the interest of the Lebanese state and its official institutions, but it is not to the interest of Hezbollah."
Officials in both the Beirut government and Iran-backed Hezbollah, which wields enormous political influence in Lebanon, have long referred to cabinet statements since 2008 enshrining the right to "resistance" as de facto official approval for Hezbollah's arsenal.
Two Lebanese officials told Reuters they did not find the added language in the new deal cause for concern, and said the most important achievement was a halt to the war.
But diplomats said the wording could give Israel more leverage than after 2006 to prevent Hezbollah from re-arming or redeploying fighters or weapons.
"Lebanon either didn't have any other option, or they think they can outsmart it," one diplomat from the region said.
A senior Western diplomat said Israel had such an upper hand, following months of heavy strikes that eliminated much of Hezbollah's top leadership and displaced more than 1.2 million people, that it could effectively dictate terms.
Hezbollah lawmaker Hassan Fadlallah was asked by a reporter on Wednesday about Israeli Prime Minister Benjamin Netanyahu's statements that Israel retained military freedom of action and would strike Hezbollah if it violated the deal.
Fadlallah said the group would retain the right to defend itself if Israel attacked.
(This story has been corrected to say that the line runs eastward from the coast, not westward, in paragraph 4)
