MCP Output Firewall MCP Server

An MCP-enabled agent reads the output of every tool it calls, and it reads that output as data. Sometimes it isn't data. Anyone with write access to a file, an issue, a database row, or a web page the agent fetches can…

Local serverstdioMIT

What is the MCP Output Firewall MCP Server?

MCP Output Firewall source profile. From the maintainer documentation: “An MCP-enabled agent reads the output of every tool it calls, and it reads that output as data. Sometimes it isn't data. Anyone with write access to a file, an issue, a database row, or a web page the agent fetches can plant text that looks like data and reads like instructions — and the model does what the text says.”

Installation

The documented npm package is mcp-output-firewall. The configuration below comes from the maintainer’s example; adapt its paths and account values to your environment.

Source

Project documentation · Repository · Discovery listing. This profile records the public documentation checked on 2026-10-08.

How to install the MCP Output Firewall MCP Server

{
  "mcpServers": {
    "firewall": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-output-firewall",
        "serve"
      ]
    }
  }
}

From the project documentation. Replace placeholders and example paths before connecting.