AI Blocks › Keep your code secure
MCP server hardener
Point it at an MCP server you run. Get a checklist of fixes for transport, auth, access and logging.
MCP server hardener is a free AI skill for the job "Keep your code secure". Give the instructions to an AI assistant that supports the required files and tools, then review its output.
Free · No account · CC BY 4.0 licence · Made by sickn33 · Level: expert
Made by sickn33. See the original on GitHub; we copied it as it is, with its licence.
What it does
A checklist of fixes that locks down an MCP server you run. It covers the connection, who may sign in, what each user may do and what gets logged. The skill starts with a threat model for MCP servers. Then it works through each layer. For the connection it gives sample TLS setups, including an Nginx proxy, mutual TLS between agent and server and how to create a client certificate. For sign-in it covers OAuth 2.1 and key handling, then access control per tool, input checks and audit logging.
You give it
- Your server setup and transport
- How users sign in today
- The tools and data it exposes
- Hosting details (optional)
You get
- A prioritised fix checklist
- TLS and mTLS sample configs
- Sign-in and key advice
- Access rules per tool
- Logging suggestions
Use it when
- You run an MCP server and plan to expose it beyond your own laptop.
- Your agents connect to the server with no encryption.
- You need per-user access to tools, not one shared key.
- A security team asked what protects your MCP server.
How to use it
- Add it to your AI once: download it and add the folder to Claude, ChatGPT or Codex as a skill.
- Ask for the job in your own words. Your AI opens the skill when it fits.
- It works best when your AI can read your project files.