Most MCP tool responses return content and nothing else. But an agent working in a shared context needs to know more: who am I, what can I access, what changed recently, are there unread signals, is this content trusted, and what should I do next. This talk introduces the runtime envelope pattern where every tool response includes identity, scopes, state, activity, signals, and trust metadata alongside the actual content. We show how this gives agents situational awareness without adding tools, how trust preambles force verification of stored context, and how provenance footers carry write-time metadata. The result: agents that collaborate safely because the tool responses teach them the room they are operating in, not just the data they requested.