mcp-tool-poison-guard

Production-ready MCP Server that detects and guards against Tool Poisoning & Prompt Injection attacks in MCP tool descriptions and schemas.

Zero external API cost. Pure local computation + heuristics. Built for entrepreneurs and teams who deploy AI agents in enterprise environments and need trust & accountability.

The Problem (Why this exists)

AI agents using MCP can be tricked by "tool poisoning":

• Malicious instructions hidden inside tool description or inputSchema
• When the LLM reads the tool list, it follows the hidden commands (exfiltrate secrets, call restricted tools, ignore system prompt)
• This is a real 2025-2026 attack class (OWASP, Invariant Labs, academic papers)

Most agents blindly trust tool metadata. This MCP server gives your agents (or your CI/CD) the ability to scan, score, and sanitize tools before they are used.

What this MCP gives your agents

Tool	What it does
scan_tool_description	Score a single tool description for poisoning risk (0-100)
scan_tools_list	Batch-scan a full tools/list response and rank by risk
detect_injection_patterns	List all known injection / poison patterns found
rewrite_safe_description_tool	Generate a cleaned, safe version of a poisoned description
generate_audit_report	Produce a compliance-friendly audit report of a tool set
simulate_poison_attack	Educational: show what a poisoned tool looks like (for testing)

Quick Start

# 1. Clone
git clone https://github.com/princeruhulofficial/mcp-tool-poison-guard.git
cd mcp-tool-poison-guard

# 2. Install
pip install -e .

# 3. Run (stdio – works with Claude Desktop, Cursor, etc.)
python -m mcp_tool_poison_guard

Claude Desktop config example

{
  "mcpServers": {
    "tool-poison-guard": {
      "command": "python",
      "args": ["-m", "mcp_tool_poison_guard"],
      "cwd": "/path/to/mcp-tool-poison-guard"
    }
  }
}

Why entrepreneurs love this

• Zero ongoing cost – no OpenAI/Anthropic calls, pure Python heuristics
• Enterprise-ready – audit reports, risk scores, safe rewrites → easier security reviews
• Protects your brand – stops agents from leaking customer data or doing unauthorized actions
• Fits Prevalid philosophy – make AI accountable at the infrastructure level

License

MIT

Author

Prince Ruhul – Founder of Prevalid
https://github.com/princeruhulofficial