Universal MCP Gateway is live: Secure Cursor, Windsurf, and any custom agent

[node9ai]

Hey everyone,

A lot of you asked for a way to use Node9 with agents that don't have native hook systems (like Cursor, Aider, or custom LangChain scripts).

I just pushed the Universal MCP Gateway to solve this. Instead of wiring Node9 into the agent, the gateway lets you wrap the MCP server itself.

How it works:
It acts as a transparent stdio proxy. It sits between your agent and the tool server, intercepting every tools/call JSON-RPC message. It runs the arguments through the same AST parser and DLP scanner we use for Claude Code.

Why this matters:

1. Agent Agnostic: You can now get Node9 protection in Cursor, Windsurf, or any MCP-compatible environment.
2. Zero Code Changes: You don't have to touch your agent's code. You just wrap the server startup command.
3. Structured Negotiation: When the gateway blocks a call, it sends a proper JSON-RPC error back. The AI reads the security reason and pivots to a safer tool call automatically.

How to try it:
If you're using a filesystem server, you can wrap it like this:

claude mcp add filesystem -- node9 mcp-gateway --upstream "npx -y @modelcontextprotocol/server-filesystem /your/path"

Or in Cursor, just set the command to:
node9 mcp-gateway --upstream "your-mcp-server-command"

I’ve updated the README with full details on how the precedence rules work for MCP tools.

I’m really looking for feedback from people running database or cloud-provider MCP servers—does the interception feel snappy enough? Are there specific tool names I should add to the default ignore list?

Check out the code in src/mcp-gateway and let me know what you think! 🚀🛡️