create-rule

A workflow for writing and testing OpenTaint rules that identify where data enters or leaves a program. Taint analysis follows potentially unsafe data through code to help find security problems.

In plain words
What is it for?
Use it to create source or sink rules for a chosen programming language and verify them against a test project.
Why use it?
It turns a package's source or destination methods into tested rules, reducing uncertainty before security relationships are connected across packages.

Skill for Claude CodeCodex

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/seqra/opentaint/create-rule
Any agent
npx skills add seqra/opentaint --skill create-rule
Clone the repo
git clone --depth 1 https://github.com/seqra/opentaint

Made for: Claude Code, Codex.

Per session 19 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,303 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 $0.00019 $0.02303
Opus 5 $0.00010 $0.01151
Sonnet 5 $0.00004 $0.00461
Haiku 4.5 $0.00002 $0.00230

Measured 2d ago against content hash 38b220c3a1f6, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

create-rule 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 2d ago.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/check-test-result.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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/create-rule/SKILL.md · 133 lines

How it starts

The opening of the file, as written. The whole thing — 133 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill: Create Rule

A unit names the source or sink methods of one side to detect. Write a library rule for each — reusing a built-in wherever one fits, authoring a custom one only for what none covers — and verify them against the unit's test project until every sample passes. Each rule exposes its tainted value under a consistent marker so a later stage can wire the real cross-package security joins. During this phase you write only the library rules and the throwaway joins to test them.

Inputs

Provided by the caller, fall back to the default value when omitted. Ask back only when a required input is missing and has no sensible default

  • project-root (optional) — root of the target project. Opentaint keeps all analysis artifacts under the fixed <project-root>/.opentaint/ directory, so every .opentaint/... path below resolves there. Default: current directory
  • language (required) — target language for this project and language-specific instructions
  • side (required) — sources or sinks; the unit's side. It selects the unit file, the sample style, and the test sub-project
  • unit (required) — the <package-kebab> identifying the unit. Its spec and tracking are in .opentaint/tracking/rules/<side>/<unit>.yaml; its test project is .opentaint/test-projects/<unit>/<side> and its compiled model .opentaint/test-compiled/<unit>/<side>
  • fix-target (optional) — a created rule <path>#<id> the main scan flagged, plus the false positive or false negative to correct. When set, narrow or broaden that one rule instead of authoring from the unit

Workflow

1. Check existing coverage

Browse the built-in library rules for a source or sink you can reference — a refs to a built-in is cheaper and more accurate than authoring a completely new rule. The following command prints the built-in rules root path; browse it (layout per the language reference) and grep by your package's FQN:

opentaint health --rules

In fix mode, don't author from the unit: go straight to that one flagged rule, adjust it by the false-positive/negative guidance per step 4, re-run this side's tests, and stop — leave the unit's other entries untouched. Otherwise, when the unit's rules already exist and pass (entries carry rule_id and stages.tests_passing: done), reuse them as the baseline and extend only for what the unit newly names. When the unit is partway (some stages done, some not), continue from the first unfinished stage on the artifacts already on disk rather than restarting, authoring from scratch only the genuinely new sources or sinks.

Read the full file on GitHub · 133 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 2d ago First seen · 133 lines · 19 tokens per session scan A 38b220c3a1f6

Subscribe to this mod's changes

create-rule is a skill published in the GitHub repository seqra/opentaint (149 stars, last pushed 3d ago), licensed Apache-2.0. It adds 19 tokens to every session and 2,303 once invoked, about $0.0001 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 2026-08-30.

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