We just wrote a ton about this, after using it.
tl;dr The spec and implementation orients towards stdio. We think this is a mistake and have created our own implementation that's backwards compatible with the spec but oriented towards production grade remote server.
MCP promises to be REST for LLMs. Imagine pointing your Claude, ChatGPT, or Gemini directly at Gmail’s (hypothetical) MCP endpoint and asking it to organize your inbox today—no custom Python wrappers, no complicated API integrations, just simple, direct communication between LLMs and servers. When you expand this to Slack, WhatsApp, banking, Uber, Twilio, GitHub, and beyond, everything becomes interconnected and actionable by language models.