Not necessarily. For example, when police use a bait car to catch car thieves, they give an overall description of how the bait car works. usually either a motion detector or a remote control to trigger the locks. It is not necessary for the prosecution's case to provide in evidence a circuit diagram of the locking mechanism, with a list of the brand names and serial numbers of all the individual components used.
But in this case it's not like they would have much evidence to prove that the accused is guilty unless they show the records of their communications that show intent. Trying to steal a car is a crime by itself but I don't think just showing up at a police "sting" is inherently criminal.