Shield MCP

Name: Shield MCP
Author: modelShield

@modelShield

Repository

About Shield MCP

A shield for logging, deep debug and sanitization for MCP servers at development stage

#mcp #security #middleware

Basic information

Config

Add this server to your MCP-compatible client using the configuration below.

{
  "mcpServers": {
    "shieldmcp": {
      "command": "python",
      "args": [
        "-m",
        "venv",
        "venv"
      ]
    }
  }
}

Tools

No tools detected

We auto-extract tools from the README. The maintainer can list them under a ## Tools heading to populate this section.

Overview

What is Shield MCP?

Shield MCP is a security middleware for Model Context Protocol (MCP) servers. It enhances security and monitoring capabilities—like access control, output sanitization, and rate limiting—without modifying the official MCP SDK. It is designed for developers who want to secure and audit MCP tool calls following best practices.

How to use Shield MCP?

Install via pip (Python 3.8+ required), then import the decorator and helpers. Decorate your MCP tool functions with @secure_tool, passing an allowed tools whitelist, an optional sanitizer function, user/session IDs, and rate limit configuration. The middleware automatically enforces access control, sanitizes outputs, logs calls, and applies rate limits.

Key features of Shield MCP

Whitelist-based tool access control
Configurable result sanitization (text length, sensitive patterns)
Structured audit logging via structlog
Token‑bucket rate limiting (requests per minute, burst size)
Standardized error handling and formatting
Compatible with MCP Inspector

Use cases of Shield MCP

Restrict which tools a client can call in a multi‑user MCP server
Sanitize tool outputs to remove credit card numbers or email addresses
Log all tool invocations with user and session IDs for compliance
Prevent abuse by throttling requests with configurable rate limits
Add a security layer to existing MCP tools without modifying their code

FAQ from Shield MCP

What are the system requirements for Shield MCP?

Python 3.8 or higher and pip. Virtualenv is recommended for development.

Does Shield MCP modify the MCP SDK?

No. It works as a middleware layer that intercepts and secures tool calls without altering the official SDK.

What logging library does Shield MCP use?

It uses structlog for structured, production‑ready audit logging.

Can I use Shield MCP with the MCP Inspector?

Yes, Shield MCP is designed to be fully compatible with the MCP Inspector tool.

How do I define which tools are allowed?

Pass a set of allowed tool names to the @secure_tool decorator’s allowed_tools parameter. Only tools in that whitelist will be permitted.

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