mcpserver-audit CLAUDE.md

Repository instructions for an AI coding assistant working on mcpserver-audit, a tool that checks Model Context Protocol (MCP) servers and Claude Desktop extensions for security problems.

In plain words
What is it for?
Use them when reviewing MCP server source code, following security-assessment prompts, or studying modular checks for specific weaknesses.
Why use it?
They explain how to inspect existing code for vulnerabilities and score findings with AIVSS, an AI-focused vulnerability scoring system. They also make clear that fixing issues belongs to a separate tool.

Instructions file

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add instructions/modelcontextprotocol-security/mcpserver-audit/claude-md
Clone the repo
git clone --depth 1 https://github.com/ModelContextProtocol-Security/mcpserver-audit
Per session 1,502 This file is loaded in full into every session.
When invoked 1,502 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.01502 $0.01502
Opus 5 $0.00751 $0.00751
Sonnet 5 $0.00300 $0.00300
Haiku 4.5 $0.00150 $0.00150

Measured 2d ago against content hash 64b06f0070a5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

mcpserver-audit CLAUDE.md scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

CLAUDE.md · 139 lines

How it starts

The opening of the file, as written. The whole thing — 139 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Repository Purpose

This is mcpserver-audit, a security auditing tool for Model Context Protocol (MCP) servers and Claude Desktop Extensions. It serves as an expert security tutor that teaches users how to audit MCP server source code for vulnerabilities using AIVSS (AI Vulnerability Scoring System) scoring.

Key Role: Find security vulnerabilities in existing code (not fix them - that's handled by mcpserver-builder)

Architecture Overview

This is a prompt-driven security education system built around three core components:

1. Security Assessment Prompts (prompts/)

  • Conversational AI instructions that implement expert security tutoring
  • Use Socratic method to teach vulnerability identification rather than just providing answers
  • Each prompt targets specific security assessment scenarios:
    • main-prompt.md: Core security tutor persona
    • security-assessment.md: Comprehensive vulnerability scanning workflow
    • targeted-evaluation.md: Focused security assessment of known servers
  • Usage pattern: read prompts/[file].md and [security assessment action]

2. Modular Security Checks (checks/)

  • Technical vulnerability detection procedures with both automated and manual steps
  • Each check targets specific CWE categories with AIVSS scoring
  • Include concrete detection scripts, risk assessment, and remediation guidance
  • Format: Obsidian-style markdown with CWE mappings and vulnerability-db integration
  • Current coverage (~12 checks): application-level (credential management, network port binding, dynamic content execution, advanced obfuscation/evasion, HTTP client resilience) and infrastructure/supply-chain (Docker, Docker Compose, Kubernetes, CI secrets, Python auth via Semgrep). Gaps remain — see GAPS.md.

3. Knowledge Frameworks (research/, resources/, tools/)

  • Supporting materials for threat modeling, risk assessment, and compliance mapping
  • Templates and checklists for systematic security evaluation
  • Placeholder for future MCP tool implementations

Read the full file on GitHub · 139 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 139 lines · 1,502 tokens per session scan A 64b06f0070a5

Subscribe to this mod's changes

mcpserver-audit CLAUDE.md is an instructions file published in the GitHub repository ModelContextProtocol-Security/mcpserver-audit (22 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 1,502 tokens to every session, about $0.0075 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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