Match each MCP transport to its defining characteristic and correct deployment scenario
stdio is a local subprocess over stdin/stdout; HTTP+SSE was the deprecated two-channel remote transport; Streamable HTTP is the current single-endpoint remote standard.
Think of three ways to talk to a helper. stdio is like passing handwritten notes to a coworker at your desk: instant, private, no phone needed. HTTP+SSE was an old long-distance setup with two separate phone lines, one to listen and one to speak, which kept dropping calls when the listen line broke. Streamable HTTP is the modern long-distance line: one number you call for everything, and it can keep streaming back to you when there is a lot to say. All three carry the same messages. They just differ in whether the helper sits beside you or lives across the network, and how reliably the line stays up.
Detailed answer & concept explanation~8 min readEverything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example. Click to expand.
Everything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example. Click to expand.
Everything you need to truly understand this topic: intuition, mechanics, step by step explanation, code, formulas, and worked example.
Everything important, quickly.
5 min: define transport versus protocol, then walk stdio (local subprocess), HTTP+SSE (deprecated two-channel), Streamable HTTP (single-endpoint current standard), and the local versus remote axis tying the match together.
| Transport | Channels | Network | Status / use |
|---|---|---|---|
| stdio | stdin/stdout, newline-delimited JSON | None, local subprocess | Current, local developer tools |
| HTTP+SSE | SSE server to client + POST client to server | Remote | Deprecated mid-2025 |
| Streamable HTTP | Single endpoint, POST + optional chunked stream | Remote | Current standard for remote servers |
Real products, models, and research that use this idea.
- Claude Desktop and Claude Code launch local filesystem and Git servers over stdio as child processes configured in a JSON config file.
- Anthropic's 2025 MCP spec revision deprecated HTTP+SSE and made Streamable HTTP the recommended transport for remote servers.
- Cloud-hosted MCP servers behind OAuth 2.1 expose a single Streamable HTTP endpoint so standard proxies and load balancers handle them cleanly.
What an interviewer would ask next. Try answering before peeking at the approach.
QWhy did the asymmetric two-channel design of HTTP+SSE cause connection lifecycle problems?
QHow does Streamable HTTP decide between a plain JSON reply and a chunked stream for a given request?
Don't say thisRed flags and common mistakes that signal junior thinking. Click to expand.
Red flags and common mistakes that signal junior thinking. Click to expand.
Calling HTTP+SSE the current remote transport. It was deprecated in 2025 and replaced by Streamable HTTP, which uses one endpoint for both directions.
The night-before-the-interview bullets. Scan these on the way to the call.
Primary sources. Skim if you want the original framing.
Same topic, related formats. Practice these next.