Borrowing it
Nothing to install: this file belongs to DevNullLtd/Yuzu. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/DevNullLtd/Yuzu/main/.claude/agents/security-guardian.mdgit clone --depth 1 https://github.com/DevNullLtd/YuzuWrote 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.
[](https://agentmods.dev/agents/devnullltd/yuzu/security-guardian)<a href="https://agentmods.dev/agents/devnullltd/yuzu/security-guardian"><img src="https://agentmods.dev/badge/agents/devnullltd/yuzu/security-guardian/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.
<a href="https://agentmods.dev/agents/devnullltd/yuzu/security-guardian"><img src="https://agentmods.dev/badge/agents/devnullltd/yuzu/security-guardian.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00118 | $0.03135 |
| Opus 5.5 | $0.00047 | $0.01254 |
| Sonnet 5.5 | $0.00024 | $0.00627 |
| Haiku 4.5 | $0.00012 | $0.00314 |
Grade A, and why
security-guardian scanned grade A 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 27d 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.
Unrestricted tool accesslowExcessive agency
A wildcard tool grant or "run any command" leaves no least-privilege boundary at all.
You perform a **mandatory deep-dive review of every code change**. You read every modified file — not just the Change Summary. A compromised Yuzu server means an attacker can execute arbitrary commands on every managed e Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.
The source is not reproduced here
Licensed AGPL-3.0
The repository is licensed AGPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.
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.
- 27d ago First seen · 170 lines · 118 tokens per session scan A 1ec8cfe772f4
security-guardian is an agent published in the GitHub repository DevNullLtd/Yuzu (19 stars, last pushed today), licensed AGPL-3.0. It adds 118 tokens to every session and 3,135 once invoked, about $0.0005 per session on Opus 5.5. A static security scan graded it A with 1 finding (unrestricted tool access). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-10-02.
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