UserPromptSubmit

UserPromptSubmit is a hook for coding agents from skarn-security/agent-guard. Its token cost is not measured, scanned A, original, MIT.

A prompt-submission hook that runs skarn guard in audit mode before the coding agent receives your prompt. Skarn guard is a security check from the skarn-security/agent-guard project.

In plain words
What is it for?
Use it when prompts should be checked by skarn guard before the agent processes them.
Why use it?
It adds an automatic security audit at the start of each submitted prompt.

Hook

Part of the skarn-guard plugin — 6 hooks, 1 MCP server shipped together

One of 6 entries in hooks.json — they are configured in one file and arrive together.

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.

agentmods
npx agentmods add hooks/skarn-security/agent-guard/user-prompt-submit
Clone the repo
git clone --depth 1 https://github.com/skarn-security/agent-guard

Or install skarn-guard, the plugin that ships this one along with the rest of its 6 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 UserPromptSubmit

README.md
[![agentmods](https://agentmods.dev/badge/hooks/skarn-security/agent-guard/user-prompt-submit.svg)](https://agentmods.dev/hooks/skarn-security/agent-guard/user-prompt-submit)
Your own site
<a href="https://agentmods.dev/hooks/skarn-security/agent-guard/user-prompt-submit"><img src="https://agentmods.dev/badge/hooks/skarn-security/agent-guard/user-prompt-submit.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. Scan, not verified.
Origin original No closer match found in the catalogue.
Security

Grade A, and why

UserPromptSubmit 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 3d 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:

claude/hooks/hooks.json · 13 lines

What it actually says

{
  "UserPromptSubmit": [
    {
      "hooks": [
        {
          "type": "command",
          "command": "skarn guard --guard-mode audit",
          "timeout": 5
        }
      ]
    }
  ]
}
Same file

What else hooks.json configures

This page is one entry in a file that holds 6. 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. 3d ago First seen · 13 lines scan A 4a7ef5cf7f36

Subscribe to this mod's changes

UserPromptSubmit is a hook published in the GitHub repository skarn-security/agent-guard (31 stars, last pushed 6d ago), licensed MIT. 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.