I am not a lawyer either, which is maybe why I am not convinced by your reasoning.

Intent - you (the person operating the agents) provided instructions and used specific models and agent parameters, that is the intent, just like writing C code and compiling intends to generate assembly code.

Sandboxing - that strengthens the intent claim, you knew it is dangerous, did you verify the sandbox is good enough for the intended purposes? Did you first run tests to try and circumvent the sandbox before letting the agents run free in the sandbox? The fact you put a string and call it a fence doesn't mean you have a fence.

We don't really need new laws, most of the cases are simpler with more educated judges and lawyers that don't fall for the AI companies' sales rhetoric. Most of the new laws actually take away the responsibility from the actual perpetrators and on to people who have no chance of controlling the tech. And to say that that is not intended will be naive, very so.