Koskamo

MCP Output Firewall

A three-layer firewall for MCP servers that provides content filtering, egress policy enforcement, and action policy determination. It inspects tool results for safe data, validates destination URLs in tool calls, and applies deterministic policies to consequential actions to prevent prompt injection, tool poisoning, and data exfiltration.

Package and access

Local package with source-attributed installation metadata. Koskamo does not execute packages during review.

MCP Output Firewall logo, by tangfei7777-cellCommunity listingLocal stdioSource reviewed; not executedPublished by tangfei7777-cell
Vendor documentation

What you can do with it

  • Inspect tool output for prompt injection or poisoned data
  • Enforce egress policies by validating tool call destinations
  • Apply action policies to block or confirm destructive tool calls

Source and maintenance

Community listingRegistry 0.3.0
mcp-registry: io.github.tangfei7777-cell/mcp-output-firewall@0.3.0Source repository
Maintenance checked

Packages and installation

Source-provided package data. Koskamo has not executed or live-probed this package.

mcp-output-firewall 0.3.0

npmnpx
mcp-output-firewall package definition
{
  "version": "0.3.0",
  "transport": "stdio",
  "identifier": "mcp-output-firewall",
  "runtimeHint": "npx",
  "registryType": "npm"
}

Tools

Reported by the attributed source; not independently observed by Koskamo.

No tool definitions available.

Connect from your client

Each snippet configures the same source-provided package; replace placeholders before use.

This server is operated by the named third party. Listing and endpoint checks are not an endorsement or a security audit. Review the operator's permissions, terms, and data handling before connecting. How listings are checked and corrected.

Cursor

Merge this local stdio configuration, replace every placeholder environment value, and restart Cursor. Koskamo has not executed this package.
Cursor configuration
{
  "mcpServers": {
    "mcp-output-firewall": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-output-firewall@0.3.0"
      ]
    }
  }
}

Cline

Merge this local stdio configuration, replace every placeholder environment value, and restart Cline. Koskamo has not executed this package.
Cline configuration
{
  "mcpServers": {
    "mcp-output-firewall": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-output-firewall@0.3.0"
      ]
    }
  }
}

VS Code

Merge this local stdio configuration, replace every placeholder environment value, and restart VS Code. Koskamo has not executed this package.
VS Code configuration
{
  "servers": {
    "mcp-output-firewall": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "mcp-output-firewall@0.3.0"
      ]
    }
  }
}

Claude Desktop

Merge this local stdio configuration, replace every placeholder environment value, and restart Claude Desktop. Koskamo has not executed this package.
Claude Desktop configuration
{
  "mcpServers": {
    "mcp-output-firewall": {
      "command": "npx",
      "args": [
        "-y",
        "mcp-output-firewall@0.3.0"
      ]
    }
  }
}

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