managing-gdl-rules

managing-gdl-rules is a skill for Claude Code, Codex from greppable/greppable-cc-plugin. It costs 100 tokens per session (758 once invoked), scanned A, original, MIT.

Instructions for creating and maintaining project-specific coding rules stored in rules.gdl files.

In plain words
What is it for?
Use them to record, review, or update rules supported by patterns found across the project.
Why use it?
They help preserve conventions that are repeatedly used in a particular codebase and distinguish them from generic programming advice.

Skill for Claude CodeCodex

Installs and runs on its own, but its text points at files inside its plugin — anything it tells you to read at a ${CLAUDE_PLUGIN_ROOT} path is only there once the plugin is installed. Installing the plugin gets both.

Part of the greppable plugin — 8 skills, 8 commands, 3 hooks shipped together

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.

agentmods
npx agentmods add skills/greppable/greppable-cc-plugin/managing-gdl-rules
Any agent
npx skills add greppable/greppable-cc-plugin --skill managing-gdl-rules
Clone the repo
git clone --depth 1 https://github.com/greppable/greppable-cc-plugin

Made for: Claude Code, Codex.

Or install greppable, the plugin that ships this one along with the rest of its 8 skills, 8 commands, 3 hooks.

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 managing-gdl-rules

README.md
[![agentmods](https://agentmods.dev/badge/skills/greppable/greppable-cc-plugin/managing-gdl-rules.svg)](https://agentmods.dev/skills/greppable/greppable-cc-plugin/managing-gdl-rules)
Your own site
<a href="https://agentmods.dev/skills/greppable/greppable-cc-plugin/managing-gdl-rules"><img src="https://agentmods.dev/badge/skills/greppable/greppable-cc-plugin/managing-gdl-rules.svg" alt="Measured on agentmods" height="20"></a>
Per session 100 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 758 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original 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 $0.00100 $0.00758
Opus 5 $0.00050 $0.00379
Sonnet 5 $0.00020 $0.00152
Haiku 4.5 $0.00010 $0.00076

Measured 4d ago against content hash 39f4c6a575df, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

managing-gdl-rules 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 4d 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.

skills/managing-gdl-rules/SKILL.md · 81 lines

How it starts

The opening of the file, as written. The whole thing — 81 lines — stays where its author put it; the contents beside it link to each section on GitHub.

GDL Rules Reference

Current Rules

!bash -c 'if [ -f rules.gdl ]; then echo "From rules.gdl:"; echo ""; grep "^@rule" rules.gdl 2>/dev/null; else echo "No rules.gdl found in project root."; fi'

What Makes a Rule Worth Writing

A rule captures a project-specific convention with codebase evidence. Not a generic best practice.

Good rule (project-specific) Bad rule (generic)
"API routes must validate input with zod schemas" "Use descriptive variable names"
"Never modify existing migrations — create new ones" "Write clean code"
"React components use PascalCase filenames" "Follow naming conventions"

The test: Can you point to 3+ files that follow this convention? If yes, it's a rule. If it's advice you'd give on any project, it's not.

When to Write vs Observe

  • Write a @rule when: you've seen the convention in 3+ files, or the user explicitly confirms it
  • Write a @memory observation when: you've noticed a pattern but aren't sure it's intentional
  • Don't write anything when: it's a language-level best practice that any linter would catch

Format

@rule|scope:GLOB|severity:LEVEL|desc:TEXT
Field Values Meaning
scope Glob pattern (*.ts, src/api/**, **/*.test.*) Which files this rule applies to
severity error Will break things if violated — wrong behavior, data loss, security
warn Convention that should be followed — consistency, maintainability
info Team preference — style, approach
desc Free text What the rule requires (imperative form)

Tool Function

source "${CLAUDE_PLUGIN_ROOT}/scripts/gdl-tools.sh"

# Check which rules apply to a file
gdl_rules_for_file "src/api/routes.ts" rules.gdl

Grep Patterns

# All rules
grep "^@rule" rules.gdl

# Rules for a specific scope
grep "^@rule|scope:src/api" rules.gdl

# All error-severity rules
grep "severity:error" rules.gdl

# Rules matching a file (fuzzy)
grep "^@rule" rules.gdl | grep "\.ts"

Read the full file on GitHub · 81 lines

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. 4d ago First seen · 81 lines · 100 tokens per session scan A 39f4c6a575df

Subscribe to this mod's changes

managing-gdl-rules is a skill published in the GitHub repository greppable/greppable-cc-plugin (3 stars, last pushed 4mo ago), licensed MIT. It adds 100 tokens to every session and 758 once invoked, about $0.0005 per session on Opus 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 2026-08-31.

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