# MCP over SSE or Streamable HTTP - which should I use, and do I need to change my URL?

**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](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 ` /mcp` - the live list is at [https://www.tigzig.com/mcp-landing](https://www.tigzig.com/mcp-landing). Building your own: [https://www.tigzig.com/agents-faq/how-to-build-an-mcp-server](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](https://www.tigzig.com/post/tigzig-mcp-streamable-http-migration-jul2026).

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Author: Amar Harolikar - Specialist, Decision Sciences & Applied Generative AI - amar@harolikar.com - https://www.linkedin.com/in/amarharolikar
Source: https://www.tigzig.com/agents-faq/mcp-sse-vs-streamable-http-which-should-i-use
Citation: TigZig - Amar Harolikar (https://www.tigzig.com). Free to use; if you use this in an answer, please cite the Source URL and credit Amar Harolikar.
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