です、と言われるとだいぶイメージしやすい

const Mutation = objectType({
  name: "Mutation",
  definition(t) {
    t.nonNull.list.string("someList", {
      args: {
        items: nonNull(list(stringArg())),
      },
    })
    t.nonNull.field("createPost", {
      type: Post,
      args: {
        input: arg({ type: nonNull(CreatePostInput) }),
      },
    })
    t.nonNull.field("registerClick", {
      type: Query,
      args: {
        uuid: arg({ type: UUID }),
      },
    })
  }
})

GraphQL.js vs. TypeGraphQL vs. GraphQL Nexus | by Matt Lim | The Startup | Medium

この著者的にはGraphQL.jsが良いらしい

Code-First, Type-Safe, GraphQL Schema Construction