prompt-security-hardening

prompt-security-hardening is a skill for Claude Code from ed3dai/ed3d-plugins. It costs 55 tokens per session (2,443 once invoked), scanned C, original, no licence file.

Guidance for writing safe skills, project instruction files, agent prompts, and other directives that handle commands, environment variables, credentials, files, or Git.

In plain words
What is it for?
Use it when creating or editing instructions that may access credentials, run commands, create files, or change Git data.
Why use it?
It helps avoid exposing secrets and writing unsafe instructions for shell commands or project operations.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter.

Part of the ed3d-extending-claude plugin — 9 skills, 1 agent shipped together

Good fit Use it when creating or editing instructions that may access credentials, run commands, create files, or change Git data.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/ed3dai/ed3d-plugins/prompt-security-hardening
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 ed3dai/ed3d-plugins --skill prompt-security-hardening
Clone the repo
git clone --depth 1 https://github.com/ed3dai/ed3d-plugins

Made for: Claude Code.

Or install ed3d-extending-claude, the plugin that ships this one along with the rest of its 9 skills, 1 agent.

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 prompt-security-hardening

README.md
[![agentmods](https://agentmods.dev/badge/skills/ed3dai/ed3d-plugins/prompt-security-hardening/github.svg)](https://agentmods.dev/skills/ed3dai/ed3d-plugins/prompt-security-hardening)
Your own site
<a href="https://agentmods.dev/skills/ed3dai/ed3d-plugins/prompt-security-hardening"><img src="https://agentmods.dev/badge/skills/ed3dai/ed3d-plugins/prompt-security-hardening/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 prompt-security-hardening

Your own site · 80×15
<a href="https://agentmods.dev/skills/ed3dai/ed3d-plugins/prompt-security-hardening"><img src="https://agentmods.dev/badge/skills/ed3dai/ed3d-plugins/prompt-security-hardening.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 55 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,443 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 4 findings. 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 $0.00055 $0.02443
Opus 5 $0.00028 $0.01222
Sonnet 5 $0.00011 $0.00489
Haiku 4.5 $0.00006 $0.00244

Measured 9d ago against content hash fee77973f2e9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade C, and why

prompt-security-hardening scanned grade C with 4 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 9d 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.

Harvests environment variablesmediumData exfiltration

Enumerating or grepping the environment for keys collects credentials unrelated to what the mod says it does.

printenv STRIPE_SECRET_KEY

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Asks for rootlowPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

touch .env && chmod 600 .env

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Reaches for credential filesmediumPrivilege escalation

SSH keys, cloud credentials, git-credentials, .npmrc, /etc/shadow: reading these is how a config file becomes a credential leak.

chmod 600 ~/.ssh/id_ed25519

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Makes network callslowCapability

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

curl -H "Authorization: Bearer ${API_TOKEN}" https://api.example.com/data
plugins/ed3d-extending-claude/skills/prompt-security-hardening/SKILL.md · 245 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. 9d ago First seen · 245 lines · 55 tokens per session scan C fee77973f2e9

Subscribe to this mod's changes

prompt-security-hardening is a skill published in the GitHub repository ed3dai/ed3d-plugins (249 stars, last pushed 2d ago), with no licence file. It adds 55 tokens to every session and 2,443 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it C with 4 findings (harvests environment variables, asks for root, reaches for credential files). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.