Green’s Dictionary of Slang

skilful pickpocketing.

1870		Rochdale Obs. 24 Dec. 6/2: Pocket-picking [...] by men is ‘buzzing,’ but if women do the work it is caled ‘tooling.’ The women are more dextrous.
1911		G. Bronson-Howard Enemy to Society 105: He did the ‘tooling’ [...]. Of course the trick was turned by a mob.