Is your feature request related to a problem? Please describe.
Unable to pass user credentials to VertexAiSearchTool

Describe the solution you'd like
Developing an agent that uses the built-in VertexAiSearchTool to retrieve an answer from Vertex AI Search datastore. To ensure the user only sees information that they are entitled to see, I want to invoke an OAuth2 credential flow so the identity used to perform the search is that of the user.

Describe alternatives you've considered
Using a custom function tool