Definition of "instrument"

The Harpe. […] A harper with his wreſt maye tune the harpe wrong / Mys tunying of an Inſtrument ſhal hurt a true ſonge

1568, William Cornishe [i.e., William Cornysh], “In the Fleete Made by Me William Cornishe otherwise Called Nyshwhete Chapelman with the Most Famose and Noble Kyng Henry the VII. His Reygne the XIX. Yere the Moneth of July. A Treatise betwene Trouth, and Information.”, in John Skelton, edited by J[ohn] S[tow], Pithy Pleasaunt and Profitable Workes of Maister Skelton, Poete Laureate, Imprinted at London: In Fletestreate, neare vnto St Dunstan-in-the-West by Thomas Marshe; republished as Pithy Pleasaunt and Profitable Workes of Maister Skelton, Poete Laureate to King Henry the VIIIth, London: Printed for C. Davis in Pater-noster Row, 1736, page 290

“There the cause of death was soon ascertained ; the victim of this daring outrage had been stabbed to death from ear to ear with a long, sharp instrument, in shape like an antique stiletto, which [...] was subsequently found under the cushions of the hansom. [...]”

1905, Baroness Emmuska Orczy, chapter 1, in The Tremarn Case‎

On the rocky island of Tungyin, 50 miles off the coast of Red China, is the headquarters of a little-known military unit called the Anti-Communist Salvation Army. The secret army, 30,000 strong, is Chiang Kai-shek's instrument for the long-promised return to the mainland.

1963 January 11, “The World”, in Time‎, volume LXXXI, number 2, page 32, column 3

Or useful serving man and instrument, / To any sovereign state.

c. 1596 (date written), William Shakespeare, “The Life and Death of King Iohn”, in Mr. William Shakespeares Comedies, Histories, & Tragedies […] (First Folio), London: […] Isaac Iaggard, and Ed[ward] Blount, published 1623, [Act V, scene ii]

The bold are but the instruments o' the wise.

1670, John Dryden, The Conquest of Granada

When the Lit. Mongers deign to notice his work, they dismiss him as a "cult writer," another of their standard ploys. Purdy, not really bitter at the instrumented silence and sneers of the bookchat legions, […]

1978 April 15, Mitzel, “An Evening and an Afternoon with James Purdy”, in Gay Community News, page 10