Thanks!

I am not aware of any automatic tool that performs an audit of OAuth2.0 implementation.

If you want to perform an audit of your implementation, DM me on Twitter (@drdr_zz). You can use the best practices that I referred to in my article ( https://tools.ietf.org/id/draft-ietf-oauth-security-topics-05.html). There are also plenty of presentation about OAuth2.0 security (e.g. Jim covers some attacks here https://www.owasp.org/images/d/d4/OWASP-NL_Chapter_Meeting201501015_OAuth_Jim_Manico.pdf) and there are also simple security checklists like https://github.com/shieldfy/API-Security-Checklist that include section related to OAuth2.0.