How to authenticate Google API toolset using an existing refresh_token?

[hborras]

Hi everyone,

I'm trying to integrate some Google toolsets like Calendar and Sheets, and I already have authentication implemented in my app.

Here's my setup:

I have a frontend application with Google login.

During login, I request access to the necessary scopes (e.g., Calendar, Sheets).

From that, I already store the user's refresh_token, along with the client_id and client_secret.

Now I’m trying to initialize the Google API toolset, but I can't find a way to authenticate using the refresh_token. It only seems to accept client_id and client_secret, without a way to inject the refresh token for actual access.

I also tried going the OpenAPI route, downloading the Discovery API JSON and initializing it via an OpenAPI tool — but still no luck in authenticating the user with the tokens I already have.

Question:
Is there any way to initialize the Google API clients with my existing refresh_token, or do I need to implement a full OAuth flow again within the toolset context?

Any help or pointers would be greatly appreciated!

Thanks 🙏