claude-security: Skill for Claude Code

.claude/skills/hat-blackbox/SKILL.md

hat-blackbox is a skill for Claude Code from anshajk/claude-security. It costs 22 tokens per session (535 once invoked), scanned A, original, no licence file.

A testing approach that checks software only through its published contract, without reading its implementation.

In plain words
What is it for?
Use it to write black-box tests for a library, service, or other tool with a defined public contract.
Why use it?
It helps reveal whether the software behaves as promised while keeping the test independent of the code behind it.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

This is anshajk/claude-security's own configuration. It tells Claude Code how to work on claude-security itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything claude-security configures →

Reuse

Borrowing it

Nothing to install: this file belongs to anshajk/claude-security. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/anshajk/claude-security/main/.claude/skills/hat-blackbox/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/anshajk/claude-security

Made for: Claude Code.

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 hat-blackbox

README.md
[![agentmods](https://agentmods.dev/badge/skills/anshajk/claude-security/hat-blackbox/github.svg)](https://agentmods.dev/skills/anshajk/claude-security/hat-blackbox)
Your own site
<a href="https://agentmods.dev/skills/anshajk/claude-security/hat-blackbox"><img src="https://agentmods.dev/badge/skills/anshajk/claude-security/hat-blackbox/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 hat-blackbox

Your own site · 80×15
<a href="https://agentmods.dev/skills/anshajk/claude-security/hat-blackbox"><img src="https://agentmods.dev/badge/skills/anshajk/claude-security/hat-blackbox.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 22 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 535 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown 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 $0.00022 $0.00535
Opus 5.5 $0.00009 $0.00214
Sonnet 5.5 $0.00004 $0.00107
Haiku 4.5 $0.00002 $0.00053

Measured 1mo ago against content hash 1e53019a301c, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

hat-blackbox 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 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

allowed-tools: Read(contracts/**), Bash(curl:*), Bash(pnpm:*)
.claude/skills/hat-blackbox/SKILL.md · 38 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

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 · 38 lines · 22 tokens per session scan A 1e53019a301c

Subscribe to this mod's changes

hat-blackbox is a skill published in the GitHub repository anshajk/claude-security (2 stars, last pushed 3mo ago), with no licence file. It adds 22 tokens to every session and 535 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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