# MCP notifications

> Tag 5: the server subscribes, once, to the notifications of the caller’s MCP servers; the client answers with one channel response per notification, an error last, and the channel response finish, each relayed to the programs in the container.

Canonical: https://protocol.diverge.network/2.3.0/container-proxy-endpoints/agents-begin/server/mcp-notifications/
Specification revision: 2.3.0

The server opens this channel at most once per connection, when a
program in the container first makes an MCP exchange of the server.
Every channel response is relayed to every MCP session the server
serves at the time it arrives.

- **The request.** The tag byte `5` and nothing more.
  [Request](/2.3.0/container-proxy-endpoints/agents-begin/server/mcp-notifications/request/) states its form.
- **The response.** One channel response per notification, an error
  last when the client sends one, and the channel response finish.
  [Response](/2.3.0/container-proxy-endpoints/agents-begin/server/mcp-notifications/response/) states the sequence.
- **Once.** The server does not open this channel a second time on the
  connection, however the first ended.