The dry law in Israel that you can carry any knife with a blade length of up to 100mm if you can prove lawful intent (yes the burden of is on you).
a folding knife that has no locking mechanism is considered by default lawful and the burden of proof is on the police officer if they think otherwise.
That said, knife carry is not 'well liked' by law authorities here and if caught with a knife, even with a perfectly lawful reason, police are still likely to cause you problems (including arrest and\or confiscation).
SAKs, keychain sized knives and multi-tools are generally ok as they are a very common sight and you're unlikely to have any problems with them (even if locking).