Can't use @better-auth/cli when exporting a auth function

$ bunx @better-auth/cli generate --config ../api/src/common/auth.ts --output ./src/schemas/auth.ts
ERROR [Better Auth]: [#better-auth]: Couldn't read your auth config in BuzzTrip/packages/api/src/common/auth.ts. Make sure to default export your auth instance or to export as a variable named auth.
error: script "db:auth" exited with code 1

export const createAuth = (
  baseUrl: string,
  authSecret: string,
  googleClientId: string,
  googleClientSecret: string,
  url: string,
  authToken: string
) => {
  const db = createDb(url, authToken);

  return betterAuth({
    // ... config
  });
};

export type Auth = ReturnType<typeof createAuth>;