Hi @jin ,
Thanks for your question and apologies for the slow reply.
This thread has a thorough discussion of some options for adding metadata to tilesets. Best practices for tileset and glTF structure and embedding metadata - #3 by 11e4c08f99c6aef7429e If the options discussed there do not meet your use case, please let us know how and share with us a bit more what you are looking for and what your contraints are.
Thanks,
Luke