Tool is an enigmatic progressive metal band from Los Angeles, California. Members include vocalist Maynard James Keenan, guitarist Adam Jones, drummer Danny Carey, and bassist Justin Chancellor. Chancellor replaced Paul D'Amour in 1995.

The band emerged with its first (and only) EP, Opiate (1992), and followed that up with their debut studio album, Undertow (1993), during the age of early 1990s grunge, and made their success by headlining Lollapalooza festivals aimed at that genre. After the alternative rock scene receded from the mainstream American ear, Tool continued into art rock and progressive rock, and have since released Ænima (1996), Lateralus (2001) and 10,000 Days (2006), which have gained worldwide critical and commercial success. After much anticipation for a fifth studio album for over 13 years, Fear Inoculum was released on August 30, 2019.

Tool’s approach has been part conviction, part sarcasm. While the band incorporates mathematical and ritualistic themes in their music, they have done so at such a level that their paradoxical belief system has hoodwinked a major part of their fan base. The band diligently utilizes multiple time signatures in all of the more recent releases, arranges their instruments into complex formations, and even incorporates the infamous Fibonacci Sequence in the song “Lateralus.”

However, for over a decade and until it was updated prior to the 2017 tour, Tool’s website offered artsy word-salad band member biographies, creating an indoctrinating, calculated mystique, and has delivered bogus news aimed at cult-like followers who are willing to believe almost anything. Messages or news the band has given, whether directly from the mouth of a band member or indirectly through the media, is meant to be taken with a grain of salt and questioned throughout, which is another ideology the band has preached for many years. Some say Tool’s approach parodies that of their long-time object of ridicule, L. Ron Hubbard and the system of beliefs he created.

Due to Tool’s incorporation of these thematic structures, visual arts (music videos made entirely from claymation), vivid and Grammy-winning album art (contributions from Adam Jones and artist Alex Grey), and very long, complex releases, the band’s sound has been described as style-transcending—a mix of progressive metal, psychedelic rock, and art rock. The relationship between the band and the music industry is ambivalent, marked by censorship and their continued insistence on privacy.

On August 2, 2019, after being held for many years, all of Tool’s music was released for digital streaming and purchase.