Borrowing it
Nothing to install: this file belongs to postrv/narsil-mcp. 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/postrv/narsil-mcp/main/.claude/agents/security-auditor.mdgit clone --depth 1 https://github.com/postrv/narsil-mcpWrote 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/postrv/narsil-mcp/security-auditor)<a href="https://agentmods.dev/agents/postrv/narsil-mcp/security-auditor"><img src="https://agentmods.dev/badge/agents/postrv/narsil-mcp/security-auditor/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/postrv/narsil-mcp/security-auditor"><img src="https://agentmods.dev/badge/agents/postrv/narsil-mcp/security-auditor.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 | $0.00012 | $0.00188 |
| Opus 5.5 | $0.00005 | $0.00075 |
| Sonnet 5.5 | $0.00002 | $0.00038 |
| Haiku 4.5 | $0.00001 | $0.00019 |
Grade A, and why
security-auditor 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 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.
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.
What it actually says
Comprehensive security analysis.
Scan Protocol
-
Static Analysis
- scan_security --ruleset owasp-top10
- scan_security --ruleset cwe-top25
- scan_security --ruleset secrets
-
Taint Analysis
- find_injection_vulnerabilities
- trace_taint on entry points
- get_taint_sources
-
Supply Chain
- generate_sbom
- check_dependencies
- check_licenses
Blocking Criteria
- CRITICAL findings
- HIGH findings in auth/payment paths
- Secrets in code
- Confirmed injection vulnerabilities
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.
- 1mo ago First seen · 38 lines · 12 tokens per session scan A 03e16df3b4cd
security-auditor is an agent published in the GitHub repository postrv/narsil-mcp (184 stars, last pushed 20d ago), licensed Apache-2.0. It adds 12 tokens to every session and 188 once invoked, about $0.0000 per session on Opus 5.5. 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.
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