I’m always a bit wary when handling tools near the live terminals of a battery.
As a general rule when disconnecting a battery to remove it you must always undo and disconnect the NEGATIVE terminal first – and last when reconnecting the terminals.
I bought a cover for the battery terminal at a recent car show and have now fitted it. During which I realised i also need covers for the two positive terminals on the back of the battery isolated switch that are also vulnerable to accidental shorting. They are now ordered visa eBay and winging their way from China over the next 6 weeks!