Koskamo

Prompt Rejector MCP

Prompt Rejector is an open-source security gateway that screens prompts, skill files, and MCP tool descriptions before an AI agent acts on them. It combines deterministic security checks with TypeSafe AI Jev judgments to detect prompt injections, jailbreaks, and tool poisoning. The server allows applications or agents to call a scanner and act on its decision, supporting various integration methods including CLI, SDK, HTTPS API, and MCP over stdio.

Package and access

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

Prompt Rejector MCP logo, by revsmokeCommunity listingLocal stdioSource reviewed; not executedPublished by revsmoke
Vendor documentation

What you can do with it

  • Detect prompt injections and jailbreaks in user inputs
  • Screen MCP tool descriptions for tool poisoning
  • Analyze skill files for security vulnerabilities
  • Block malicious instructions before agent execution

Source and maintenance

Community listingRegistry 1.0.1
mcp-registry: io.github.revsmoke/promptrejectormcp@1.0.1Source repository
Maintenance checked

Packages and installation

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

prompt-rejector 1.0.1

npm
prompt-rejector package definition
{
  "version": "1.0.1",
  "transport": "stdio",
  "identifier": "prompt-rejector",
  "registryType": "npm",
  "environmentVariables": [
    {
      "name": "YOUR_API_KEY",
      "format": "string",
      "isRequired": true,
      "description": "Your API key for the service"
    }
  ]
}

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": {
    "prompt-rejector-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "prompt-rejector@1.0.1"
      ],
      "env": {
        "YOUR_API_KEY": "<YOUR_YOUR_API_KEY>"
      }
    }
  }
}

Cline

Merge this local stdio configuration, replace every placeholder environment value, and restart Cline. Koskamo has not executed this package.
Cline configuration
{
  "mcpServers": {
    "prompt-rejector-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "prompt-rejector@1.0.1"
      ],
      "env": {
        "YOUR_API_KEY": "<YOUR_YOUR_API_KEY>"
      }
    }
  }
}

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": {
    "prompt-rejector-mcp": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "prompt-rejector@1.0.1"
      ],
      "env": {
        "YOUR_API_KEY": "<YOUR_YOUR_API_KEY>"
      }
    }
  }
}

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": {
    "prompt-rejector-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "prompt-rejector@1.0.1"
      ],
      "env": {
        "YOUR_API_KEY": "<YOUR_YOUR_API_KEY>"
      }
    }
  }
}

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