Mutual. [She tilts her head and closes an eye.] The flow of mana can be perceived by some. The best way to hide it is to keep the flow as close as possible to zero except when needed. And then there are the command seals. A red mark that will appear on the back of your dominant hand.

[ Okay, here comes the lengthy explanation. Sighs, why does she have to keep explaining her world lore? It's so stupid! The woes of being a goddess... ]

You see, if a mage summons a powerful heroic spirit - what's to stop that "Servant" from killing their summoner and finding an alternate source of mana to survive in the human world? [A pause.] To prevent such a scenario, the contract grants the mage three command seals that can be used to compel obedience from their Servant if needed. However, those command seals are a limited quantity.

[ She beckons for the cat that's at her feet, to take it on her lap and pet it. Ehehe, cats are so cute! And well-behaved too. ]

Of course, that's for contracts where the two parties do not trust each other. [Not their case, or she wouldn't be here in the first place. Besides those rules were made for heroic spirits, as a divine spirit it would be harder to compel obedient in her.] You, however, could use those command seals to greatly empower my next attack. Think of it like allowing me to temporarily break my limits. [You could even call it... A limit break!] You could also summon me to your side in case of emergency.

[ Like if say, a friendly kaiju suddenly becomes murderous. ]