Question 34
Domain 4Which schema field in a tool input is *most* likely a smell that auth has leaked into the wrong layer?
Correct answer: B
Explanation
`bearer_token` is a smell because a bearer token is an authentication credential, and auth should usually be handled outside the tool’s business input schema. A required field named "bearer_token" suggests the tool is directly consuming secrets instead of receiving an already-authenticated context or scoped identity.
Why each option is right or wrong
A. `to_email` (string).
`to_email` is normal business data for sending a message, not an auth credential.
B. `bearer_token` (string, required).
A required `bearer_token` field is the clearest sign that the tool schema is carrying an authentication secret as business input, rather than operating on an already-established identity context. In OAuth 2.0, a bearer token is itself the credential that grants access (RFC 6750, §1.2), so placing it in the tool’s input contract means the tool is directly responsible for secret handling instead of being invoked under an authenticated session or scoped principal. The fact that it is marked required makes the smell stronger: every call must supply a live credential, which is exactly the layer leakage the question is testing.
C. `subject` (string).
`subject` describes message content and does not indicate identity or authorization handling.
D. `body` (string).
`body` is application payload, so requiring it does not imply auth leaked layers.