OP mentioned particle emitters as an example, including relative position to the attached object. To me, that would infer client-side variables for distance, intensity, translucency, etc.
Hence me mentioning obfuscation and encoding the values in some way, if OP isn't going to use server validation and tamper checking.
The BattleTech example I gave - well, they did have heat levels, damage done, range, etc, all part of the JSON. If memory serves. Hence mentioning the different rulesets that one could put up. Until they locked down and did tamper checking.