in a sitch like this, false positives are much preferable to false negativves =P
hemiscorpius lepturus have pretty thick claws, all things considered. and wimpy little tails.
Probably the best thing when out collecting. Know what's around you then the size of the claw or size of the tail shouldn't be an issue.i was collecting when i first started the hobby and i got stung by a scorpion with fairly little claws. i can tell you... it was not a comfortable hour or two when i was in the middle of nowhere racking my brain as to what was dangerously venomous in the area.
as it turns out it was just a vaejovid... but it really impressed upon me the need to KNOW about the bugs that could be dangerous in any areas you are collecting in. i wasted that hour or two sitting quietly in the shade trying to keep my heart rate and other metabolic processes depressed while doing some thinking... when i could have been catching more bugs =P