The Coast Guard lacked an effective vessel sized between its Island-class patrol boat and the Reliance-class Medium Endurance Cutter, so there was considerable interest in Cyclone at first.

Originally armed with two Mk38 25 mm chain guns fore and aft, several pintle mounts for attaching .50 caliber machine guns or Mk 19 grenade launchers, and a position for launching Stinger shoulder-fired SAMs (although this was removed when the ship was transferred to the Philippine Navy and is currently unavailable), the ship, along with others of her class still in the US Navy, were upgraded early on by replacing the after Mk.38 mount with the new Mk.96 platform.

AN/SAT-2A infrared signaling systems are fitted, and the Marconi Vistar stabilized FLIR sensor with integral low-light-level television camera is mounted on the mast.

Main propulsion is generated by four Paxman Valenta 16CM-16RP200M diesels, developing 3,350 bhp, driving 12.8 cm six-blade highly skewed, variable pitch and rake, NI-AL bronze MIL-B24480A, alloy 1 amendment 3 (nickel-aluminum-bronze alloy) propellers, with pitch ratio of 1.465 at 0.7 radius and designed by USN NSWCCD (Code 544 drawing number P-5237B).

[8] Refitted by Bollinger Machine Shop and Shipyard prior to delivery[2] and received a stern ramp modification upgrade known as the Combat Craft Retrieval System (CCRS) which had the ship's stern extended by nine feet to accommodate a deck ramp - which extends down to below the water line, for a 20 feet Rigid Hull Inflatable Boat (RHIB).

[9] In April 2018, the BRP General Mariano Alvarez intercepted the Mongolian-registered M/V Diamond 8 after seeing some suspicious movement by the foreign vessel skippered by a Chinese national named Lin Yang Yin.

Upon further investigation, approximately 27,180 sacks of Vietnam rice weighing 1,359 metric tons with an estimated market value of P67,950,000 was found on board the ship, along with 34 undocumented Filipinos, one of whom was a minor.

[12] In May 2018, the ship participated in the Third Combined Maritime Security Activity with the Royal Australian Navy (RAN) along with Cebu, Anastacio Cacayorin, Dioscoro Papa and Filipino Flojo.

[13] In September 2018, General Mariano Alvarez participated in the Fifth Combined Maritime Security Activity in Zamboanga City, with the RAN which sent HMAS Launceston (ACPB 94).

The activity benefited both navies in terms of inter-operability training while complementing the maritime security operations of Western Mindanao Command by enhancing Naval presence and deterrence of movement of lawless elements at sea.

The activities of the exercise include a Capability Demonstration, Day Tours and Sports aimed at strengthening relations, enhancing mutual cooperation and interoperability of the three navies.