# agent_mcp The bridge that exposes a C+ app's [agent surface](/docs/agent-surface) to an external agent over **MCP**. It speaks JSON-RPC 2.0 — `describe_ui`, `actions`, and `events` — over Unix-domain sockets: - `serve_uds` — serve on a Unix-domain socket path. - `serve_fd` — serve on an already-open file descriptor. Every request passes through an [agent_core](/docs/packages/agent_core) consent `AuthGate` before it reaches the app, so the wire protocol grants no authority of its own: the same consent and affordance-ceiling rules apply whether a call arrives in-process or over the socket. Point an MCP client at the socket to let an agent describe, drive, and observe the app. The `appkit_agent` recipe wires this together with [agent_appkit](/docs/packages/agent_appkit).