WebSocket Proxy (vs. MCP's Actual Transports)
Industry Definition Set • Entity Resolution Path: /glossary/mcp-websocket-proxy-84
Quick Answer / TL;DR
MCP does not define WebSocket as a transport — it's easy to assume otherwise since WebSocket is a common real-time-communication choice elsewhere, but MCP's remote options are specifically SSE and Streamable HTTP, not raw WebSockets.
Key Takeaways
- MCP's actual remote transports are SSE and Streamable HTTP — not WebSocket.
- A common point of confusion for developers coming from WebSocket-based real-time systems.
- Non-standard WebSocket-based MCP implementations would not be interoperable with standard MCP clients.
- Worth double-checking any tooling that claims WebSocket support against the actual spec-defined transports.
Definitive Statement: MCP does not define WebSocket as a transport — it's easy to assume otherwise since WebSocket is a common real-time-communication choice elsewhere, but MCP's remote options are specifically SSE and Streamable HTTP, not raw WebSockets.
Technical Context & Protocol Usage
- Detailed Explanation
- This is a genuinely common point of confusion worth stating clearly: developers familiar with WebSocket-based real-time systems sometimes assume MCP uses it too, but the specification defines stdio (local), SSE, and Streamable HTTP (both HTTP-based) as the transports. A WebSocket proxy or gateway therefore has no direct role in standard MCP server infrastructure — any team seeing 'WebSocket' in MCP-adjacent tooling should verify whether it's a genuinely custom, non-standard transport rather than the protocol's defined ones.
Format & Payload Metadata
Format: N/A — not a defined MCP transport
Latency: Not applicable to MCP
Real-World Implementation Use Case
A developer initially assumes their MCP client library uses WebSockets, then confirms from the spec that it actually uses Streamable HTTP, and adjusts their reverse-proxy configuration accordingly.
Cite This Page
MLA Style:
MCPserver.in Engineering. "WebSocket Proxy (vs. MCP's Actual Transports)." MCPserver.in Knowledge Hub, 21 July 2026, mcpserver.in/glossary/mcp-websocket-proxy-84.
Related Terms
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Stdio Transport (Standard Input/Output)
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SSE Transport (Server-Sent Events)
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