- "A very special ability that allows Jeff to size up the enemy and report all weaknesses to you."
- — EarthBound Player's Guide
Spy is an ability exclusive to Jeff in EarthBound. When used in battle, it will display the foe's attack and defense stats, alongside one of their PSI weaknesses. It can also be used to steal items from enemies (if they possess item). It is very useful when hunting for "1/128" items, thus defeating the enemy is unnecessary. Note that if you don't get an item by spying the first time, the enemy most likely does not have one at all.
- Spy is the Earthbound equivalent to the Check command used by everyone in EarthBound Beginnings and the Sniff command used by Boney in Mother 3 .
- When Jeff has confusion (feeling strange), he may Spy on Ness, Paula, Poo or even himself.