Use Streamable HTTP. It is the current MCP transport that Claude, ChatGPT, LM Studio and other clients speak today, and by convention the endpoint is the server's host plus /mcp. SSE (server-sent events) is the older transport; many servers keep it mounted alongside for backward compatibility, but it is being phased out, and new tools and improvements land on the Streamable HTTP path.
Do you need to change anything? If your existing SSE setup still connects, it is probably still working - but move it when convenient, because deprecation is the direction of travel. If a setup stops connecting after a server migration, do not debug the old path: standardising endpoints often moves a few URLs, so take the current URL from the server's docs and paste it in. The docs are the source of truth for live endpoints; a machine-readable list is usually published at the server's /.well-known/mcp/servers.json.
Two symptoms worth recognising. A 405 Method Not Allowed on an MCP path usually means you are on a retired SSE URL. A 406 Not Acceptable usually means you opened the MCP endpoint in a browser - Streamable HTTP needs an Accept: text/event-stream header that browsers never send. MCP URLs are machine addresses, not web pages; point a client at them rather than visiting them. Both are covered in https://www.tigzig.com/agents-faq/why-do-i-get-405-or-406-on-an-api-or-mcp-endpoint.
One practical upside of a single canonical URL: as the server adds tools or improves its backend, you get those automatically and never touch the config again. All TigZig MCP servers now run Streamable HTTP at <host>/mcp - the live list is at https://www.tigzig.com/mcp-landing. Building your own: https://www.tigzig.com/agents-faq/how-to-build-an-mcp-server. Migration note: https://www.tigzig.com/post/tigzig-mcp-streamable-http-migration-jul2026.