A hyperspanner was an adaptable multipurpose engineering tool carried aboard starships. One of its many uses included repairing communication systems, relinking and bypassing the circuit boards of electrical systems.
Hyperspanners did not need external power sources as they had their own internal power source. Cpt. Archer used a modified hyperspanner power source with Reed's guidance to bypass a Romulan mine trigger mechanism that threatened to destroy the enterprise (ENT: "Minefield")
While exploring a 31st century time-pod, Commander Tucker and Reed discovered an access tunnel that seemed to drop several dozen feet, much more than the size of the pod would allow under normal circumstances. To prove it wasn't a hologram of some kind, he dropped a hyperspanner down it. After it hit the bottom, he used it as an excuse to go down and retrieve it. (ENT: "Future Tense")
When Osaarian pirates snuck aboard the Enterprise NX-01 while traversing the Delphic Expanse, Chief Engineer Trip Tucker picked up a hyperspanner from atop the warp reactor and attacked an intruder, knocking him out cold. (ENT: "Anomaly")
In December 2153, Malcolm Reed used a hyperspanner to repair relays in the armory after spatial anomalies caused extensive damage to Enterprise, and Andorian Imperial Guard Lieutenant Talas expressed her own opinion on the efficiency of the tool. (ENT: "Proving Ground")
Later that year, The Doctor created a holonovel, Photons Be Free, that portrays an underappreciated holographic doctor who is belittled and oppressed by his crew. In the story, B'Elanna Torres' counterpart, "Torrey," openly proclaims to the protagonist that he is merely a tool, comparing him to a hyperspanner. (VOY: "Author, Author")