mcp-security-reviewer

mcp-security-reviewer is a skill for Claude Code, Codex from oxbshw/LLM-Agents-Ecosystem-Handbook. It costs 34 tokens per session (391 once invoked), scanned A, original, MIT.

A security review procedure for MCP servers, which are add-ons that give an agent extra tools or data sources. It checks the server's source code, permissions, network connections, tool risks, and approval requirements.

In plain words
What is it for?
Use it before adding an MCP server, adopting a new version, or reviewing one after an incident. It produces a documented review with risk labels and human-approval rules.
Why use it?
It helps identify what a new or updated server can access before connecting it to an agent. This reduces the risk of excessive permissions, unsafe tool output, unexpected network access, or unapproved actions.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it before adding an MCP server, adopting a new version, or reviewing one after an incident. It produces a documented review with risk labels and human-approval rules.

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Install with agentmods
npx agentmods add skills/oxbshw/llm-agents-ecosystem-handbook/mcp-security-reviewer
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.

Any agent
npx skills add oxbshw/LLM-Agents-Ecosystem-Handbook --skill mcp-security-reviewer
Clone the repo
git clone --depth 1 https://github.com/oxbshw/LLM-Agents-Ecosystem-Handbook

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for mcp-security-reviewer

README.md
[![agentmods](https://agentmods.dev/badge/skills/oxbshw/llm-agents-ecosystem-handbook/mcp-security-reviewer/github.svg)](https://agentmods.dev/skills/oxbshw/llm-agents-ecosystem-handbook/mcp-security-reviewer)
Your own site
<a href="https://agentmods.dev/skills/oxbshw/llm-agents-ecosystem-handbook/mcp-security-reviewer"><img src="https://agentmods.dev/badge/skills/oxbshw/llm-agents-ecosystem-handbook/mcp-security-reviewer/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for mcp-security-reviewer

Your own site · 80×15
<a href="https://agentmods.dev/skills/oxbshw/llm-agents-ecosystem-handbook/mcp-security-reviewer"><img src="https://agentmods.dev/badge/skills/oxbshw/llm-agents-ecosystem-handbook/mcp-security-reviewer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 34 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 391 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 5.1 $0.00034 $0.00391
Opus 5 $0.00017 $0.00196
Sonnet 5 $0.00007 $0.00078
Haiku 4.5 $0.00003 $0.00039

Measured 12d ago against content hash 698e80acf561, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

mcp-security-reviewer 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 12d 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.

skills/examples/mcp-security-reviewer/SKILL.md · 42 lines

What it actually says

MCP Security Reviewer

When to use

  • A new MCP server is being added to an agent
  • An MCP server version is being bumped
  • An incident triggered a re-review

Inputs

Name Type Required Notes
repo_url string yes the MCP server's source
version string yes tag or commit SHA being adopted
intended_use string yes one paragraph: what we'll let it do

Workflow

  1. Source review: clone at the pinned version; check for unexpected files / scripts
  2. Capabilities: list every tool and resource exposed; map to risk levels (references/mcp-risk-matrix.md)
  3. Network: identify outbound endpoints; document and assess each
  4. Permissions: minimum required scopes / tokens; document over-permissions
  5. Output handling: confirm the agent treats tool output as untrusted (sanitization, no execution)
  6. Approvals: define which tools require human approval
  7. Produce filled MCP_SERVER.md in mcp/<server>.md

References

Success criteria

  • All tools labelled by risk
  • High/Critical tools gated by approval
  • Pinned version (no latest / floating refs)
  • Documented network egress

Failure modes

  • Source unavailable / un-pinnable → reject
  • Discovered hidden tool not in docs → reject and report upstream
Files

What ships with it

1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 12d ago First seen · 42 lines · 34 tokens per session scan A 698e80acf561

Subscribe to this mod's changes

mcp-security-reviewer is a skill published in the GitHub repository oxbshw/LLM-Agents-Ecosystem-Handbook (546 stars, last pushed 2mo ago), licensed MIT. It adds 34 tokens to every session and 391 once invoked, about $0.0002 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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