I'm currently adding extra properties to some graphql object field definitions, like the following:

const MutationType = new GraphQLObjectType({
  name: 'Mutation',
  fields: () => ({
    AddSomething: {
      // ... normal field properties
      somethingElse: {},
    }
  }),
})

And then using them later on via the info argument inside some middlewares (using graphql-middleware):

const mutationField = info.schema.getMutationType().getFields()[info.fieldName];
console.log(mutationField.somethingElse);

For more details, see the following medium post: graphql mutation arguments validation using yup

The thing is, this is relying on internal behavior.
The following code spreads all properties given to the field:

Is that something expected to not change? If yes, then no need for any other extra property or for this issue. 😄

But if this is something that can change in future versions, I would love the possibility of having an extra field for that extra metadata.

I'm available to work on adding this, if it's approved.