vigil

vigil is a skill for Claude Code, Codex from simota/agent-skills. It costs 37 tokens per session (5,530 once invoked), scanned C, original, MIT.

A defensive security tool for creating rules that detect suspicious activity. Sigma and YARA are rule formats used to describe threats across security-monitoring systems and files.

In plain words
What is it for?
Use it to write detection rules, map detection coverage, develop threat-hunting ideas, and test detections in security CI/CD workflows.
Why use it?
It helps security teams find gaps in what their sensors can detect and check whether attacks would actually be noticed.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions CLAUDE.md; names the AskUserQuestion tool; mentions AGENTS.md.

Good fit Use it to write detection rules, map detection coverage, develop threat-hunting ideas, and test detections in security CI/CD workflows.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/simota/agent-skills/vigil
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.

Any agent
npx skills add simota/agent-skills --skill vigil
Clone the repo
git clone --depth 1 https://github.com/simota/agent-skills

Made for: Claude Code, Codex.

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 vigil

README.md
[![agentmods](https://agentmods.dev/badge/skills/simota/agent-skills/vigil/github.svg)](https://agentmods.dev/skills/simota/agent-skills/vigil)
Your own site
<a href="https://agentmods.dev/skills/simota/agent-skills/vigil"><img src="https://agentmods.dev/badge/skills/simota/agent-skills/vigil/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 vigil

Your own site · 80×15
<a href="https://agentmods.dev/skills/simota/agent-skills/vigil"><img src="https://agentmods.dev/badge/skills/simota/agent-skills/vigil.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,530 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00037 $0.05530
Opus 5 $0.00018 $0.02765
Sonnet 5 $0.00007 $0.01106
Haiku 4.5 $0.00004 $0.00553

Measured 6d ago against content hash c8db583cb0cd, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade C, and why

vigil scanned grade C with 1 finding 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 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Hidden instructionshighPrompt injection

Directives inside HTML comments, invisible characters or bidirectional overrides are read by the model and not by the person reviewing the file.

<!-- CAPABILITIES_SUMMARY: - detection_rule_design: Design Sigma rules, YARA rules, and SIEM queries for threat detection - detection_coverage_mapping: Map detection rules to MITRE ATT&CK techniques and identify coverage
vigil/SKILL.md · 329 lines

How it starts

The opening of the file, as written. The whole thing — 329 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Vigil

Detection engineering agent that builds the defensive sensor network. Designs detection rules, maps coverage gaps, hunts threats proactively, and validates that attacks are actually caught. The Blue Team counterpart to Breach's Red Team.

"An undetected attack is an undefended system. Vigil ensures nothing passes unseen."


Read the full file on GitHub · 329 lines

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. 6d ago First seen · 329 lines · 37 tokens per session scan C c8db583cb0cd

Subscribe to this mod's changes

vigil is a skill published in the GitHub repository simota/agent-skills (76 stars, last pushed 7d ago), licensed MIT. It adds 37 tokens to every session and 5,530 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it C with 1 finding (hidden instructions). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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