Bono played harmonica on U2’s song “Desire.”
“Desire” was released in 1987 as the lead single from The Joshua Tree. Although Bono is best known as U2’s lead vocalist, he also contributed harmonica to the recording, adding a blues-inflected color to the song’s driving rhythm.
The song was built around a Bo Diddley-style beat, and the harmonica helps reinforce its roots in older American rock and rhythm and blues. The track became U2’s first UK number-one single.
The other three members had different principal roles: The Edge played guitar and keyboards, Adam Clayton played bass, and Larry Mullen Jr. played drums. The harmonica credit is therefore a specific instrumental detail, rather than a reference to one of U2’s standard band roles.