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mcp-sse-transport-deprecated ​

SSE transport is deprecated, use HTTP or WebSocket instead

Warning

Rule Details ​

The Server-Sent Events (SSE) transport for MCP servers is deprecated in favor of the HTTP streamable transport. This rule emits a warning whenever a server has type set to "sse" so that configurations can be migrated before SSE support is removed entirely. The HTTP transport offers better bidirectional communication and is the recommended replacement.

Incorrect ​

Server using the deprecated SSE transport

json
{
  "mcpServers": {
    "remote": {
      "type": "sse",
      "url": "https://mcp.example.com/sse"
    }
  }
}

Correct ​

Server using the recommended HTTP transport

json
{
  "mcpServers": {
    "remote": {
      "type": "http",
      "url": "https://mcp.example.com/api"
    }
  }
}

Server using WebSocket transport

json
{
  "mcpServers": {
    "remote": {
      "type": "websocket",
      "url": "wss://mcp.example.com/ws"
    }
  }
}

How To Fix ​

Change the server type from "sse" to "http" and update the url to point to the HTTP streamable endpoint. Alternatively, use "websocket" if the server supports it.

Options ​

This rule does not have any configuration options.

When Not To Use It ​

Disable this rule if you are intentionally targeting an MCP server that only supports the SSE transport and cannot be upgraded.

Resources ​

Version ​

Available since: v0.2.0