When you choose a target and click the espionage button, a picture like this one appears. If the target is a Robber_Barron, (or equivalent in other maps), then you can perform only military espionage. If the target is another player, you can perform either military or economic espionage.
In both cases, you can define the number of the agents and the percentage of desired accuracy of the result. Increasing the two factors, will increase the cost in coins, for the mission.
One thing, most players don’t understand, is how the risk of being caught is calculated from the system.
If you have, lets say 15 agents, you have the option to do two different things:
1. Send all of them at once, with a risk e.g. 5%.
2. Send them at 15 different times, with risk e.g. 90%.
Mathematically, most players assume that the first option is better, but statistics states that with the 2nd option you have more chances to aquire the report.
The problem with the 2nd option is that the opponent will know 100% that you have performed espionage against him, because most of your agents will be caught.