Describe the bug
The specification states for the GET stream

These messages SHOULD be unrelated to any concurrently-running JSON-RPC request from the client.

However, the official MCP example servers like everything send progress notifications on the GET stream. These are directly related to a concurrently-running JSON-RPC request.

Its unclear if this is a case of the server not following a SHOULD, the spec being unclear on what 'related' means, or something else

To Reproduce
Steps to reproduce the behavior:

1. Run everything MCP server
2. Call longRunningOperation
3. Observe progress notifications about the tool call are on the GET stream