Describe the bug
It may be helpful to determine if a server is "alive" by sending a ping request before attempting to initialize a connection.

The specification currently states:

However, it does not explicitly state that ping MUST be supported before initialize.

Even the documentation on ping doesn't state that it must be supported before initialize.

https://modelcontextprotocol.io/specification/2025-03-26/basic/utilities/ping

As such, at least the Rust SDK does not seem to not support ping before initialize:

Here's a test with the rust MCP SDK:

curl 'http://localhost:5050/mcp' \
  -H 'accept: application/json, text/event-stream' \
  -H 'content-type: application/json' \
  --data-raw '{"jsonrpc":"2.0","id":1,"method":"ping","params":{}}'
Unexpected message, expect initialize request%