Security & Testing·v0.6.2" # x-release-please-version

ggshield — Check HasMySecretLeaked (HMSL) Agent Skill

Check whether a known credential has already leaked publicly via GitGuardian's HasMySecretLeaked (HMSL) hash-lookup service.

Context cost
9.1k tokensestimated from the bundle, loaded when it triggers
Bundle
3 files · 36.5 kBtext throughout, nothing executable
Licence
MITthe author’s own terms
Last change
—v0.6.2" # x-release-please-version
Servers it uses
Noneruns standalone

What it does

Check whether a known credential has already leaked publicly via GitGuardian's HasMySecretLeaked (HMSL) hash-lookup service. Use when the user inherits credentials, suspects a specific token leaked, wants to vet a HashiCorp Vault inventory, or asks "has this secret leaked", "is this compromised", or "check against HMSL". Distinct from scan-secrets, which finds unknown secrets in code; this checks known secrets against the HMSL corpus.

What this skill changes about the agent has not been set out here as a list. Its SKILL.md, shown below, says it in the author’s own words.

securitytesting

The skill itself

A skill is instructions the model reads, so you can see what you are getting: below is the start of its SKILL.md. The front matter loads with every session, the body loads when the skill triggers, and the whole file comes with the install.

SKILL.md18.2 kB · preview
--- name: check-hmsl license: MIT compatibility: Requires the ggshield CLI, version 1.49.0 or later. The user runs the commands, not the agent. A GitGuardian account is optional, since HMSL runs anonymously with a lower quota. metadata: command-handoff: "true" version: "0.6.2" # x-release-please-version ---
11# ggshield — Check HasMySecretLeaked (HMSL)
12
13> **STOP — read before proceeding.** This skill is user-run only. The agent must not invoke ggshield hmsl check, fingerprint, query, decrypt, or check-secret-manager. The agent must not call Read, Grep, cat, head, tail, sed, awk, or any other tool against credential files, .env-style files, vault dumps, or HMSL intermediate files (*-payload.txt, *-mapping.txt, *.dump). The single agent job is to prepare commands for the user to execute in their own terminal, then interpret sanitized output the user pastes back (-n none --json only). Continuing past this block constitutes acknowledgement of the user-run model. If you arrived here as a follow-up from scan-secrets (e.g., to resolve validity: no_checker findings), do not extend the agent-executable contract of that skill into this one — they have different execution models.
14
15## Overview
16
17HMSL ([hasmysecretleaked.com](https://www.hasmysecretleaked.com/)) is GitGuardian's public hash-lookup service for known secrets. You bring a credential, HMSL tells you whether it's been seen leaking in GitGuardian's currently indexed public GitHub sources (public repositories, commits, gists, and issues). The plaintext credential never leaves the machine — ggshield hashes it locally and, by default, submits hash prefixes only.
18
19This is the inverse of scan-secrets. scan-secrets finds *unknown* secrets in files you control. check-hmsl checks *known* secrets you already have against the public-leak corpus: a .env you inherited from a former teammate, a token someone pasted into Slack, a credential dump from a possibly-compromised system, or the full inventory of a secret manager.
20
21## The privacy property HMSL provides — and the agent-context risk
22
23ggshield hmsl check <file> does this dance, entirely on the user's machine until the underlined step:
24
251. Read the file.
262. SHA-256 each secret.
273. Put a hash prefix for each secret into the payload.
284. <ins>Send the payload to HMSL.</ins> ← only this leaves the machine
295. HMSL returns all known leaked hashes that share each prefix.
This is a preview of SKILL.md. Download or install the skill to get the whole thing.
In the file
SKILL.md2,753 words
Files3
LicenceMIT
Why you can read it

Nothing in a skill executes. The client loads the text and the model follows it, so a skill can be audited the way a runbook is — by reading it.

What it costs in context

Skills are not billed by the call. They are paid for in context: every token the instructions occupy is a token your code, your diff and your conversation cannot use. Here is what this one takes and when it takes it.

≈240
always loaded
The name and description, so the model knows the skill exists and when to reach for it.
8,885
on trigger
The instruction body and 2 supporting files, read only when the skill fires.
4.6%
of a 200k window
Ten skills this size would take about 46% of the window before you open a file.
050k100k150k200k context window

9.1k tokens, estimated from the bundle at four bytes to the token, held for the rest of the session once it triggers. Heavy. Teams tend to install this one per project rather than globally, and load it only when the job comes up.

Servers bill, skills cost

A server charges by the month. A skill charges once per session, in context, and then keeps charging it for as long as the session lives.

Before and after

The same question, put to the same model twice: once as it comes, and once with these instructions loaded.

No worked example has been published for this skill yet.

The procedure it runs

The procedure has not been set out here step by step. It is in the body of its SKILL.md: the start of it is shown above, and the whole file comes with the install.

Prose, not code

These steps are written for a model to follow, not executed by a runtime. It can still be told to skip one, and it will say so when it does.

Servers it uses

None. This skill calls no MCP servers at all.

Everything it needs is in the instructions, so it works in a project with nothing connected — the model reads the file and changes how it works with what it can already reach.

Its SKILL.md does not declare which tools it asks the agent for, so what it touches is whatever the instructions themselves ask for — read them before you install it.

What it asks for
Writes filesnot declared
Network accessnot declared

This SKILL.md carries no allowed-tools line, so neither is declared. A skill grants no permissions of its own — it can only ask for tools your client already has.

What it will not do

Every skill is narrow, and the useful ones say where they stop. These are the jobs this one is the wrong tool for.

What this skill is not for has not been published here. Nothing is implied by that: it is a section the author has not filled in.

What is in the bundle

3 files, 36.5 kB on disk. A bundle is text throughout: the instructions the model reads, plus the templates it fills in.

  • SKILL.md18.2 kB
  • references/ggshield-cli-setup.md12.7 kB
  • references/gitguardian-platform.md5.6 kB
What is not in it

No dependencies and nothing executable: a skill is text the agent reads, so the bundle is 3 files you can review in full before installing. The MIT licence covers the templates and examples as well as the instructions.

Install

Installing copies the bundle into your project. Nothing runs at install time — the files sit on disk until the model reads them.

# ggshield — Check HasMySecretLeaked (HMSL) · 9.1k tokens when loaded · macOS, Linux mkdir -p .claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/ggshield-check-hasmysecretleaked-hmsl/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/ggshield-check-hasmysecretleaked-hmsl" ] && { [ ! -e .claude/skills/ggshield-check-hasmysecretleaked-hmsl ] || { mv .claude/skills/ggshield-check-hasmysecretleaked-hmsl "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/ggshield-check-hasmysecretleaked-hmsl" .claude/skills/ && echo "Installed .claude/skills/ggshield-check-hasmysecretleaked-hmsl"
On Windows, or any OS with Node 20+
npx mcprush@latest skill add gitguardian/ggshield-check-hasmysecretleaked-hmsl

Windows PowerShell says 'running scripts is disabled on this system'? Run Set-ExecutionPolicy -Scope CurrentUser RemoteSigned once, or type npx.cmd instead of npx (codex.cmd, gemini.cmd, grok.cmd likewise). PowerShell 7 needs neither. Writes to .claude/skills/ggshield-check-hasmysecretleaked-hmsl/ in the current project. For every project instead, run mkdir -p ~/.claude/skills && t=$(mktemp -d) && curl -fsSL -o "$t/bundle.tar.gz" https://mcprush.com/api/skills/ggshield-check-hasmysecretleaked-hmsl/bundle.tar.gz && tar -xzf "$t/bundle.tar.gz" -C "$t" && [ -d "$t/ggshield-check-hasmysecretleaked-hmsl" ] && { [ ! -e ~/.claude/skills/ggshield-check-hasmysecretleaked-hmsl ] || { mv ~/.claude/skills/ggshield-check-hasmysecretleaked-hmsl "$t/.previous" && echo "Previous copy moved to $t/.previous"; }; } && mv "$t/ggshield-check-hasmysecretleaked-hmsl" ~/.claude/skills/ && echo "Installed ~/.claude/skills/ggshield-check-hasmysecretleaked-hmsl" (macOS, Linux) — or add --global to the npx line. The curl line replaces .claude/skills/ggshield-check-hasmysecretleaked-hmsl/ only after the download succeeds, so files left there by another skill of the same name, or by an older release, do not mix in. A copy already there is moved aside, not deleted, and the line prints where. It appears as check-hmsl in Gemini CLI, Codex, Copilot and Grok (its own name); Claude Code lists it by the folder name, ggshield-check-hasmysecretleaked-hmsl.

Which clients pick it up on their own

A skill is a folder of text. Most of these read a skills folder and pick it up without being told; the rest take the same folder another way — an upload in the app, a parameter on an API call — and then choose it by its description just the same.

Claude Code.claude/skills/
Claude DesktopCustomize › Skills
ChatGPTSkills › Create › Upload
Cursor.cursor/skills/
VS Code.github/skills/
Codex CLI.agents/skills/
Gemini CLI.gemini/skills/
Grok Build.grok/skills/
Microsoft CopilotSkills › Upload a skill
PerplexityComputer › Skills › Upload a skill
DeepSeek Harness.dsh/skills/
Zed.agents/skills/
Devin Desktop.devin/skills/
Windsurf (legacy).windsurf/skills/
OpenAI Agents SDKInstructions or sandbox Skills
HTTP / APIa request parameter
This release
Version0.6.2" # x-release-please-version
Publishedno release date on file
PriceFree
Referencegitguardian/ggshield-check-hasmysecretleaked-hmsl

Versions

v0.6.2" # x-release-please-version is what is on the shelf; no release here carries a date. Instructions change more often than APIs do — a skill can be rewritten entirely without anything it depends on moving.

v0.6.2" # x-release-please-version
  • No earlier releases have been published to the marketplace.
Pinning

The install command always fetches the release that is current the day you run it — v0.6.2" # x-release-please-version today — and cannot ask for an earlier one. The copy on your disk does not change until you run it again.

Reviews

—no reviews yet

Nobody has reviewed this skill yet. The rating is the mean of the reviews written here, so there is none until somebody writes the first.

Sign in to review it

A review is tied to an account so it can be answered, edited and taken down by the person who wrote it.

Sign in
Who can post

Anybody with an account, one review each. It carries the version that was current when you wrote it, and the publisher may reply once.

Publisher
Servers0
Claim this skill