How is this different from the existing MCP support in Claude Code?

Existing MCP support was for the stdio and SSE transport protocols which are either local MCP servers in docker/node/python or a remote server but still requiring a sort of workaround running locally in the form of the mcp-remote non package.

This now natively supports the latest streamable http transport protocol and the server is entirely remote, nothing is running on your local machine it's just an url (usually ending with /mcp, although not mandatory it's usually true and distinguishes from /sse servers).