JsonLogic Skill

An agent skill that teaches AI coding assistants to work with JsonLogic business rules: turn a plain-language requirement into a valid JsonLogic rule, run it, validate it, explain it, or debug it.

Works with Claude Code, Cursor, GitHub Copilot, VS Code, Codex, and Gemini CLI. Install it once and your AI assistant picks it up automatically whenever JsonLogic comes up, in any project.

Install

Claude Code:

git clone https://github.com/valeryia-piatrova/jsonlogic-skill.git ~/.claude/skills/jsonlogic

Restart Claude Code to pick it up.

Every install path differs by client: each badge below jumps to that client's exact command in docs/installing.md:

What It Does

Your AI assistant uses this JsonLogic skill automatically when JsonLogic comes up.

• Turn a plain-language business requirement into a valid JsonLogic rule
• Run a JsonLogic rule against your data
• Validate whether a JsonLogic rule is well-formed
• Explain what an existing JsonLogic rule does
• Debug a JsonLogic rule that returns the wrong result

Usage

No data shape given:

Give a 20% discount on orders over $200, or 10% over $100, otherwise no discount

Approve a claim only if the policy is active and the incident happened after the policy start date, but route it to manual review instead if the policyholder already has 2+ claims this year, or if the amount is over the coverage limit

Let a user edit a document if they are the owner or an admin, but only while the document is not locked for review

Flag a transaction as suspicious if it is over $5,000 and happens outside business hours, unless the account has 90+ days of history and no prior flags, in which case just log it instead of blocking

Data shape given (field names come from it, not a guess):

Approve a claim, but route it to manual review instead of auto-approving if the policyholder already has 2+ claims this year or the amount is over the limit.

Explain what this JsonLogic rule does:

{
	"some": [
		{ "var": "items" },
		{ ">": [{ "var": "price" }, 500] }
	]
}

Run this JsonLogic rule in Ruby:

{
	">=": [{ "var": "age" }, 18]
}

Why does this rule return false when I expect true?

{
	"rule": { "and": [
		{ ">": [{ "var": "total" }, 100] },
		{ "==": [{ "var": "vip" }, true] }
	]},
	"data": { "total": 150, "vip": "true" }
}

Uses operators from the real JsonLogic standard. Checks whether the standard and your language's library actually support the logic you need, and says so plainly if they don't.

FAQ

What is the JsonLogic skill?

An open-source agent skill (MIT licensed) that gives AI coding assistants reliable JsonLogic abilities: writing, running, validating, explaining, and debugging JsonLogic business rules.

Which AI assistants does it work with?

Claude Code, Cursor, GitHub Copilot, VS Code (agent mode), Codex, and Gemini CLI, plus any other client that supports the open Agent Skills format from agentskills.io.

What is JsonLogic?

JsonLogic is a JSON-based format for portable business rules and conditional logic. One rule runs across JavaScript, Python, Ruby, PHP, Java, and more.

How is this different from asking ChatGPT or Claude to write JsonLogic directly?

The skill encodes the real JsonLogic standard, per-language operator support, and a validate-before-you-answer workflow, so you get rules that actually run instead of plausible-looking guesses.

Do I need to install anything else?

No. The skill is a folder of Markdown plus small scripts. Clone it into your client's skills directory and restart the client.

Is it free?

Yes. MIT license, free for personal and commercial use.

Learn More

• jsonlogic.com: the standard this skill implements
• SKILL.md: full workflow and reasoning

License

MIT, see LICENSE.