Like empaths, telepaths are measured by the range, strength, sensitivity and their control of their ability.
Control is the same across all the Psi. A person needs to get a minimum rating of 75% control to get a level three rating in control and thereby qualify for testing above a level three in their abilities. This is because a high rated telepath isn’t any use if they can’t work on command, I mean, unless you want to turn them into a telepathic bomb or something similarly disgusting.
Range is similar to the empath ratings except the distances increase. Level one is touch-only, so that any affect they can bring about can only happen if they are touching their target. Level two is generally somewhere between the conversational distance and line sight. Level three is approximately a kilometre distance, but only with one target. Level four is a max of five kilometres radius. Level five is between five kilmetres and ten. Most people can only deal with one or two targets as a telepath, or multiple targets but one at a time within their sense radius. The Agency had to expand their ratings as telepaths got stronger. And while I don’t have all of the distances, Jaola, who rates at an 8 telepath, can just contact across the distance between the nearest edges of two cities, so, that’s as much as someone talking in Auckland with someone in Wellington (almost 700km/400 miles).
For a telepath strength is more literal than for empaths. Telepaths have a sort of telepathic body that has a sort of mass that can cause damage to minds if the telepath isn’t gentle. The stronger the telepath, the harder they have to work to not do damage to those whose minds they enter. The Agency measures telepathic strength by the damage done while training the telepath. Which, because I’m not a brutal dictator organisation, means that I can’t give you exact measurements for this. Except that it’s a linear scale. A level five telepath, say Bana Malar, at full strength can enter a non-telepathic mind and completely annihilate their mental pathways, effectively killing them… in the worst way possible. A level three, say Hawk, at full strength might put someone in a coma for a few days but probably wouldn’t kill them. A level one, is likely to simply give someone a migraine. Jaola, for example, can mash a brain in a microsecond of inattention. She’s so strong that even when she’s being as gentle as possible she still causes severe damage in other telepaths.
Sensitivity, is how much a telepath can sense from the outside world by default (without shielding). So, level one is, predictably, touch-only. If you can only sense thoughts with touch, you’re always a level one regardless of the content or accuracy of what you’re sensing. Level two is basically being able to talk telepathically with someone else, without touch. You can only hear the thoughts that they’ve formed into words, and no others. Level three sensitivity is being able to hear the rumble of normal thoughts of a non-telepath, both the formed words and the wordless thoughts. Levels four and five are typically about volume. A level five without shielding will die from the pain generated from the noise in their head. A level four won’t die but they’ll suffer a great deal (which is why the primary training focus is Control, because part of control is learning shielding). Jaola, at level eight can, with physical contact, actually get into the parts of the mind that are only accessible when people do a full Interrogation, but without stripping the mind. Given the right training, Jaola is sensitive enough that she could recreate a person’s entire mental network to become an entirely new person, but neither she nor the Agency knows that she’s this sensitive (so shh don’t tell them).d