PreToolUse

PreToolUse is a hook for Claude Code from NVIDIA/NeMo-Relay. Its token cost is not measured, scanned A, original, Apache-2.0.

A command that forwards every tool call to a local NeMo Relay gateway before the call proceeds.

In plain words
What is it for?
Use it when tool calls must be forwarded through NeMo Relay before execution.
Why use it?
It sends tool-use events to the relay and blocks the call if forwarding fails.

Hook for Claude Code ✓ vendor

Written for Claude Code: PreToolUse hook event.

Part of the nemo-relay-plugin plugin — 14 hooks, 1 MCP server shipped together

One of 14 entries in hooks.json upstream. Installing this one merges just its entry into your config; the other 13 are separate, each on its own page.

Good fit Use it when tool calls must be forwarded through NeMo Relay before execution.

Compare 6 hooks from other repositories ↓
Install with agentmods
npx agentmods add hooks/nvidia/nemo-relay/pre-tool-use
About the project

NVIDIA/NeMo-Relay is a runtime and library that gives coding agents and applications shared control over agent execution scopes, policies, plugins, lifecycle events, and observability data. It is for developers who need to inspect or instrument runs from agents such as Codex or Claude Code, or integrate frameworks and export traces and trajectories. The catalogue entries provide Relay plugins, hooks, instructions, skills, and an MCP server for those workflows.

NVIDIA/NeMo-Relay · 196 stars · on GitHub · docs.nvidia.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/NVIDIA/NeMo-Relay

Made for: Claude Code.

Or install nemo-relay-plugin, the plugin that ships this one along with the rest of its 14 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/nvidia/nemo-relay/pre-tool-use/github.svg)](https://agentmods.dev/hooks/nvidia/nemo-relay/pre-tool-use)
Your own site
<a href="https://agentmods.dev/hooks/nvidia/nemo-relay/pre-tool-use"><img src="https://agentmods.dev/badge/hooks/nvidia/nemo-relay/pre-tool-use/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 PreToolUse

Your own site · 80×15
<a href="https://agentmods.dev/hooks/nvidia/nemo-relay/pre-tool-use"><img src="https://agentmods.dev/badge/hooks/nvidia/nemo-relay/pre-tool-use.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

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 1mo 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.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

integrations/coding-agents/claude-code/hooks/hooks.json · 14 lines

What it actually says

{
  "PreToolUse": [
    {
      "matcher": "*",
      "hooks": [
        {
          "type": "command",
          "command": "nemo-relay hook-forward claude --gateway-url http://127.0.0.1:47632 --forward-only --fail-closed",
          "timeout": 30
        }
      ]
    }
  ]
}
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. 1mo ago First seen · 14 lines scan A a789750dbbc9

Subscribe to this mod's changes

PreToolUse is a hook published in the GitHub repository NVIDIA/NeMo-Relay (196 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 2026-08-30.