Agent Native

add-and-validate-guardian-developer-semgrep-rule

This skill helps developers write custom Semgrep rules and add them to Guardian to enforce project conventions or catch patterns Guardian's standard rules miss.

by SemgrepOfficial publisherNot reviewed

Identity proven by GitHub's verified organisation badge (semgrep)

Agents
Claude Code
License
No license stated
Pin
f488aadpinned Oct 9, 2026
Context cost
about 2,100 tokenswhen the skill loads
GitHub stars
16on semgrep/guardian
Scripts
None found

What it does

“write a custom semgrep rule with the user, add it to guardian in either user or repo scope, and prove it fires by writing a file that should trip it. use when someone wants guardian to catch something it currently misses, asks to write or add a semgrep rule, or wants a project convention enforced on the code claude writes.”
The author's description, from SKILL.md

Generated summary from the skill's own text

This skill helps developers write custom Semgrep rules and add them to Guardian to enforce project conventions or catch patterns Guardian's standard rules miss. The agent collaborates with the user to craft a rule, adds it to either user or repository scope, and validates it by writing test files that should trigger the rule.

When to use it

  • Enforcing project-specific code conventions or style requirements
  • Catching deprecated internal APIs or footgun patterns your team needs blocked
  • Adding a rule to Guardian's scanner when the deployment's existing ruleset has gaps
  • Validating that a new Semgrep rule fires correctly before committing it

When not to

  • When developer rules are disabled in your Semgrep deployment
  • When you need cross-file analysis or call graph patterns that single-file scans cannot detect
  • If the rule would require more disk space or rule count than your deployment's limits allow

Install

No license stated: install from the publisher's repository, and ask the author before you reuse or share it.

These commands install from the publisher's repository and need no account.

skills CLI

npx skills add semgrep/guardian --skill add-and-validate-guardian-developer-semgrep-rule

Installs from the repository's default branch, which may have changed since the commit we checked.

GitHub CLI 2.90 or later

gh skill install semgrep/guardian add-and-validate-guardian-developer-semgrep-rule@f488aadb860337ecdcb7dfc1ce7f6ec3a61ace43

Installs the commit we checked (f488aad).

Copy by hand

Download the folder at f488aad and put it in .claude/skills/add-and-validate-guardian-developer-semgrep-rule for Claude Code and in .agents/skills/add-and-validate-guardian-developer-semgrep-rule for Codex, Cursor, Gemini CLI, GitHub Copilot and OpenCode.

Skill folder on GitHub at f488aad

Claude Code plugin

/plugin install semgrep@claude-plugins-official

The publisher's plugin in Claude's official marketplace. It may hold more than this skill, and we have not pinned it.

Copy for your agent

A prompt for any coding agent. It installs this skill from GitHub at the pinned commit, copies the files as they are, and runs nothing unless you ask.

Prompt

Install the agent skill "add-and-validate-guardian-developer-semgrep-rule" by Semgrep.

Source, pinned to commit f488aadb860337ecdcb7dfc1ce7f6ec3a61ace43:
https://github.com/semgrep/guardian/tree/f488aadb860337ecdcb7dfc1ce7f6ec3a61ace43/plugin/skills/add-and-validate-guardian-developer-semgrep-rule

1. Download that folder at exactly this commit. Do not use the default branch.
2. Copy every file unchanged, keeping the folder structure, into .claude/skills/add-and-validate-guardian-developer-semgrep-rule/ for Claude Code and .agents/skills/add-and-validate-guardian-developer-semgrep-rule/ for Codex, Cursor, Gemini CLI, GitHub Copilot and OpenCode. Create the folders if they do not exist.
3. Do not edit the files, and do not run any script in the folder unless I ask you to.
4. When you are done, list the files you copied and where you put them.

Its license is restricted or not stated. Show me the license terms from the repository before you copy anything.

Listing and checks: https://www.agentnative.dev/skills/semgrep/add-and-validate-guardian-developer-semgrep-rule

SKILL.md at the pin

The license of this skill does not let us show its files here.

View SKILL.md on GitHub at f488aad

Files

1 file, 8.8 KB in total. Each file has a sha256 in the pin's manifest; the first 12 characters are shown.

Skill folder on GitHub at f488aad
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The skills listed here are third-party software, collected from public GitHub repositories as a catalog of recent skills and provided as is. Agent Native does not write or control them and is not responsible for any harm, loss or damage caused by installing or using them. Labels and checks describe what we saw at one commit and are not a guarantee. Read a skill's files before you run it. Terms of use