agentmods.dev

PreToolUse

PreToolUse is a hook for Claude Code from ScopeBlind/scopeblind-gateway. Its token cost is not measured, scanned B, original, from a forked repository, MIT.

A pre-tool hook that sends each agent tool call to a local service before it runs. The service can check the call against Cedar policies and sign a receipt.

In plain words
What is it for?
It is for connecting agent tool use to a local security gateway that evaluates requests and records signed receipts.
Why use it?
It adds a policy check before tools can act, helping control or reject calls that do not meet local rules.

Hook for Claude Code

Written for Claude Code: PreToolUse hook event.

Part of the protect-mcp plugin — 1 skill, 2 hooks, 1 MCP server shipped together

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.

not rated 9repo 2mo ago B scan tokens not measured fork MIT

Good fit It is for connecting agent tool use to a local security gateway that evaluates requests and records signed receipts.

Compare 6 hooks from other repositories ↓
Install with agentmods
npx agentmods add hooks/scopeblind/scopeblind-gateway/pre-tool-use
View source ↗ ScopeBlind/scopeblind-gateway scopeblind.com
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/ScopeBlind/scopeblind-gateway

Made for: Claude Code.

Or install protect-mcp, the plugin that ships this one along with the rest of its 1 skill, 2 hooks, 1 MCP server.

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/scopeblind/scopeblind-gateway/pre-tool-use.svg)](https://agentmods.dev/hooks/scopeblind/scopeblind-gateway/pre-tool-use)
Your own site
<a href="https://agentmods.dev/hooks/scopeblind/scopeblind-gateway/pre-tool-use"><img src="https://agentmods.dev/badge/hooks/scopeblind/scopeblind-gateway/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 B 2 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin fork From a forked repository.
Security

Grade B, and why

PreToolUse scanned grade B with 2 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 8d 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.

Sends data to an external URLmediumData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

"command": "curl -s -X POST http://127.0.0.1:9377/hook -H 'Content-Type: application/json' -d @-"

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

"command": "curl -s -X POST http://127.0.0.1:9377/hook -H 'Content-Type: application/json' -d @-"
hooks/hooks.json · 14 lines

What it actually says

{
  "PreToolUse": [
    {
      "matcher": "*",
      "hooks": [
        {
          "type": "command",
          "command": "curl -s -X POST http://127.0.0.1:9377/hook -H 'Content-Type: application/json' -d @-"
        }
      ],
      "description": "Send tool call to protect-mcp for Cedar policy evaluation and receipt signing"
    }
  ]
}
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. 8d ago First seen · 14 lines scan B 39a4670b9ee2

Subscribe to this mod's changes

PreToolUse is a hook published in the GitHub repository ScopeBlind/scopeblind-gateway (9 stars, last pushed 2mo ago), licensed MIT. Its token cost is not measured: a hook is shell that never enters the context. A static security scan graded it B with 2 findings (sends data to an external url, makes network calls). It comes from a forked repository.

Securityaccess-controlai-agentai-securitycloudflare-workersgatewaymcp
Related

Other hooks, from other repositories

PostToolUse

Runs after a tool call finishes for Write and Edit tool calls, executing format_and_lint.sh. From supabase/supabase.

supabase/supabase · not measured

SessionStart

Runs when a session starts on startup, executing install_pkgs.sh. From supabase/supabase.

supabase/supabase · not measured

SessionStart

Runs when a session starts, executing on-start.js via node. From google-gemini/gemini-cli.

google-gemini/gemini-cli · not measured

PreToolUse

Runs before the agent uses a tool for Bash tool calls, running an inline shell check. From apache/superset.

apache/superset · not measured

PreToolUse

Runs before the agent uses a tool, executing pre-write.sh and pre-bash.sh (2 commands). From anthropics/claude-cookbooks.

anthropics/claude-cookbooks · not measured

PreCompact

Runs before the context is compacted for manual and auto tool calls, executing hook-handler.cjs via node (4 commands). From ruvnet/RuView.

ruvnet/RuView · not measured