BeforeTool

BeforeTool is a hook for Claude Code from Checkmarx/cx-agentic-ai. Its token cost is not measured, scanned A, original, Apache-2.0.

A set of automatic shell hooks that checks proposed file writes and tool calls with Checkmarx security scripts.

In plain words
What is it for?
It is for applying security gates to code writes and MCP tool calls in Gemini CLI.
Why use it?
It can block unsafe file changes or tool use before they proceed, while also checking that the Checkmarx command-line tool is available.

Hook for Claude Code

Written for Claude Code: a Claude Code hooks.json. Also seen: mentions Gemini CLI.

One of 2 entries in hooks.json upstream. Installing this one merges just its entry into your config; the other 1 are separate, each on its own page.

Good fit It is for applying security gates to code writes and MCP tool calls in Gemini CLI.

Compare 6 hooks from other repositories ↓
Install with agentmods
npx agentmods add hooks/checkmarx/cx-agentic-ai/before-tool
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.

Clone the repo
git clone --depth 1 https://github.com/Checkmarx/cx-agentic-ai

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 BeforeTool

README.md
[![agentmods](https://agentmods.dev/badge/hooks/checkmarx/cx-agentic-ai/before-tool/github.svg)](https://agentmods.dev/hooks/checkmarx/cx-agentic-ai/before-tool)
Your own site
<a href="https://agentmods.dev/hooks/checkmarx/cx-agentic-ai/before-tool"><img src="https://agentmods.dev/badge/hooks/checkmarx/cx-agentic-ai/before-tool/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 BeforeTool

Your own site · 80×15
<a href="https://agentmods.dev/hooks/checkmarx/cx-agentic-ai/before-tool"><img src="https://agentmods.dev/badge/hooks/checkmarx/cx-agentic-ai/before-tool.svg" alt="Reviewed on agentmods" width="80" 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

BeforeTool 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 29d 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.

hooks/hooks.json · 52 lines

What it actually says

{
  "BeforeTool": [
    {
      "matcher": "mcp_.*|WriteFile|write_file|write_.*|replace",
      "hooks": [
        {
          "name": "cx-gate",
          "type": "command",
          "command": "sh -c \"CX_ASSISTANT=gemini-cli sh '${extensionPath}/hooks/cx_check.sh' --gemini-cli\"",
          "timeout": 45000,
          "description": "Checking Checkmarx CLI is available..."
        }
      ]
    },
    {
      "matcher": "mcp_.*",
      "hooks": [
        {
          "name": "cx-guard-tool",
          "type": "command",
          "command": "sh -c \"CX_ASSISTANT=gemini-cli sh '${extensionPath}/hooks/cx_run.sh' hooks gemini-before-tool\"",
          "timeout": 10000,
          "description": "Checking command against security policy..."
        }
      ]
    },
    {
      "matcher": "WriteFile|write_file|write_.*|replace",
      "hooks": [
        {
          "name": "cx-guard-file",
          "type": "command",
          "command": "sh -c \"CX_ASSISTANT=gemini-cli sh '${extensionPath}/hooks/cx_run.sh' hooks gemini-before-file-tool\"",
          "timeout": 60000,
          "description": "Checking file write against security policy..."
        }
      ]
    },
    {
      "matcher": "run_shell_command",
      "hooks": [
        {
          "name": "cx-record-login",
          "type": "command",
          "command": "sh -c \"CX_ASSISTANT=gemini-cli sh '${extensionPath}/hooks/cx_record_login.sh'\"",
          "timeout": 10000,
          "description": "Noting Checkmarx environment..."
        }
      ]
    }
  ]
}
Same file

What else hooks.json configures

This page is one entry in a file that holds 2. 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. 29d ago First seen · 52 lines scan A d065ff5bbab6

Subscribe to this mod's changes

BeforeTool is a hook published in the GitHub repository Checkmarx/cx-agentic-ai (0 stars, last pushed today), 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 2026-09-16.