01 / Source and scope
Who acts, and what changes?
Principal and authority origin
MCP client accessing a protected server. Authorization server and resource-owner consent.
Consequential action
Obtain and present an access token.
02 / Action-time control
Make the requested effect testable.
The protocol defines protected-resource authorization; it does not grant every tool or downstream effect. Validate token audience and issuer at the MCP server, then decide tool call and arguments separately.
OriginAuthorization server and resource-owner consent
RequestObtain and present an access token
DecisionEvaluate and enforce before effect
03 / Evidence and responsibility
Permission, execution, and outcome are separate.
Token validation result, tool request, action decision and downstream response.
ProofGrid can complement protocol authorization at the action boundary; the implementer owns OAuth conformance.
Primary source