Maybe a slightly weaker variant: I agree not to develop autonomous weapons that can harm humans or other living beings. The idea being that it's ok to develop

Maybe a slightly weaker variant: I agree not to develop autonomous weapons that can harm humans or other living beings. The idea being that it's ok to develop an autonomous weapon that would cripple the enemy's production capabilities without harming people. Or one that would guard against other autonomous weapons. If you can build them, so can your enemies and you shouldn't presume they won't. Edit: Or imagine swarms of tiny robots that destroy firearms, or disable fire systems, etc. These should be fine to develop.