Glossary
MCP transport (stdio and Streamable HTTP)
How an MCP client reaches a server: stdio launches it as a local subprocess; Streamable HTTP posts JSON-RPC to a URL. The tools are identical either way.
MCP separates what a server offers from how it is reached. Over stdio the client spawns the server as a local process and speaks JSON-RPC on its pipes, which is how most npm- and Docker-packaged servers run. Over Streamable HTTP the client posts JSON-RPC to a URL, optionally upgrading to a server-sent event stream, which is how a hosted server is reached without installing anything.
The distinction matters for checking. A hosted endpoint can be probed from outside: initialize, then tools/list, and a parked domain cannot fake either. A stdio server can only be checked by installing and running it, which is why a reproduced install is a separate kind of evidence.
Neither transport says anything about what the tools do or whether their answers are correct. It only says how the conversation is carried.
Where Sato Hub measures it
- How many listed MCP servers answer the handshake →
- Success rate of our daily checks, by probe method →
Numbers live on those pages and refresh on their own schedule; this definition does not restate them.
Related terms
Sources
Cite this page
Sato Hub. "MCP transport (stdio and Streamable HTTP) (glossary)." Sato Hub, updated 2026-09-14, accessed 2026-09-14. https://satohub.ai/glossary/mcp-transportData last refreshed 2026-09-14; this page is rebuilt daily. Citations carry the date so a reader can tell which snapshot a claim came from. Catalog data is licensed CC-BY-4.0.