Is it a covenant or an equitable servitude?
"Equitable enforcement of covenants restricting the use of land was recognized in the common law of England after the middle of the Nineteenth Century. Equitable servitudes are distinguished from covenants running with the land in that the latter should be of record, and a buyer takes with constructive knowledge, if not actual knowledge, of the existence of such recorded covenants and is thereby bound to the covenants.
The question of enforceability does not depend on whether the covenant runs with the land ... if there was a mere agreement and no covenant [running with the land], this court would enforce it against the party purchasing with notice of it; for if an equity is attached to the property by the owner, no one purchasing with notice of that equity can stand in a different situation from the party from who he purchased.
Equitable interests may arise because of the actions of the parties, such as oral representations." West Wood Investments, Inc. v. Acord, 106 P.3d 401, 409-410 (Idaho 2005).