We say it's best practice to use a single input type as an argument, and then we do this:

type Mutation {
 createUser(user: CreateUserInput!, secretKey: String!): User
}

I created it that way because secretKey felt like something out of band, like you'd put it in a header, except it's more convenient to be an argument given it's only used in this one resolver. Is that a good reason, in which case we could add an explanation, or should we just move it inside the input object like this?

input CreateUserInput {
 firstName: String!
 lastName: String!
 username: String!
 email: String!
 authId: String!
 secretKey: String!
}

Thanks to @Borales for asking