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mcp-contrast: Hook for Claude Code

.claude/settings.json

PreToolUse is a hook for Claude Code from Contrast-Security-OSS/mcp-contrast. Its token cost is not measured, scanned A, original, Apache-2.0.

A pre-action security check that runs before an agent reads, writes, edits, or executes shell commands.

In plain words
What is it for?
It is for applying the archunit-store-guard.sh check to Read, Write, Edit, and Bash tool calls.
Why use it?
It helps prevent those actions from bypassing the project's architectural storage rules.

Hook for Claude Code

Written for Claude Code: $CLAUDE_PROJECT_DIR variable.

This is Contrast-Security-OSS/mcp-contrast's own configuration. It tells Claude Code how to work on mcp-contrast itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything mcp-contrast configures →

One of 3 entries in settings.json — they are configured in one file and arrive together.

not rated 23repo 2d ago A scan tokens not measured original Apache-2.0
View source ↗ Contrast-Security-OSS/mcp-contrast
Reuse

Borrowing it

Nothing to install: this file belongs to Contrast-Security-OSS/mcp-contrast. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/Contrast-Security-OSS/mcp-contrast/main/.claude/settings.json
Clone the repo
git clone --depth 1 https://github.com/Contrast-Security-OSS/mcp-contrast

Made for: Claude Code.

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 PreToolUse

README.md
[![agentmods](https://agentmods.dev/badge/hooks/contrast-security-oss/mcp-contrast/pre-tool-use.svg)](https://agentmods.dev/hooks/contrast-security-oss/mcp-contrast/pre-tool-use)
Your own site
<a href="https://agentmods.dev/hooks/contrast-security-oss/mcp-contrast/pre-tool-use"><img src="https://agentmods.dev/badge/hooks/contrast-security-oss/mcp-contrast/pre-tool-use.svg" alt="Measured on agentmods" height="20"></a>
Per session not measured What this adds to a session before it is invoked.
When invoked not measured Not applicable: nothing here is loaded into a session.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Security

Grade A, and why

PreToolUse 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 7d ago.

A static scan of the commands this hook runs, not an audit. A hook is shell that executes on your machine at the event it names, which is why every command in it is printed with what was found.

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/settings.json · 14 lines

What it actually says

{
  "PreToolUse": [
    {
      "matcher": "Read|Write|Edit|Bash",
      "hooks": [
        {
          "type": "command",
          "command": "$CLAUDE_PROJECT_DIR/.claude/hooks/archunit-store-guard.sh",
          "timeout": 5
        }
      ]
    }
  ]
}
Same file

What else settings.json configures

This page is one entry in a file that holds 3. Installing the file brings all of them; each is measured and scanned on its own page.

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. 7d ago First seen · 14 lines scan A 9625fc308d48

Subscribe to this mod's changes

PreToolUse is a hook published in the GitHub repository Contrast-Security-OSS/mcp-contrast (23 stars, last pushed 2d ago), licensed Apache-2.0. Its token cost is not measured: a hook is shell that never enters the context. 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.

Security
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