Everything we have built so far runs on a single machine. Your MCP server launches as a subprocess, your client talks to it over stdio, and both live on the same laptop. That works well for local development, personal tools, and desktop apps like Claude Desktop or Cursor. But the moment you need to share an MCP server across a team, expose it to cloud-hosted agents, or run it on a different machine than your client, stdio falls apart.

Stdio is a local transport. It requires the client to spawn the server process directly. There is no URL to point at, no port to connect to, no way for a client running on Machine A to talk to a server running on Machine B. If you want five developers on your team to use the same MCP server that wraps your company's internal APIs, each developer would need to install the server locally, configure credentials on their machine, and keep everything in sync. That does not scale.

This is the problem that remote MCP servers solve. Instead of communicating through stdin/stdout pipes, the server exposes an HTTP endpoint that any client on the network can connect to. The MCP specification defines a transport called Streamable HTTP for exactly this purpose.

It gives you the familiar request-response pattern of HTTP for regular tool calls, plus Server-Sent Events (SSE) for real-time streaming when the server needs to push notifications or progress updates to the client.