toon

toon is a skill for Claude Code from hackermanishackerman/claude-skills-vault. It costs 44 tokens per session (1,692 once invoked), scanned A, a copy of toon, MIT.

A compact text format for representing JSON data for language models. It uses indentation for objects and table-like rows for lists of similar items.

In plain words
What is it for?
Converting JSON into the TOON format and back, especially for sending structured data to language models or storing uniform lists compactly.
Why use it?
It can make structured data shorter and easier for a language model to process than standard JSON. It also supports checking list lengths and converting data back to JSON without loss.

Skill for Claude Code

Written for Claude Code: installed under .claude/. Also seen: reads .claude/ paths.

Good fit Converting JSON into the TOON format and back, especially for sending structured data to language models or storing uniform lists compactly.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/hackermanishackerman/claude-skills-vault/toon
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.

Any agent
npx skills add hackermanishackerman/claude-skills-vault --skill toon
Clone the repo
git clone --depth 1 https://github.com/hackermanishackerman/claude-skills-vault

Made for: Claude Code.

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 toon

README.md
[![agentmods](https://agentmods.dev/badge/skills/hackermanishackerman/claude-skills-vault/toon.svg)](https://agentmods.dev/skills/hackermanishackerman/claude-skills-vault/toon)
Your own site
<a href="https://agentmods.dev/skills/hackermanishackerman/claude-skills-vault/toon"><img src="https://agentmods.dev/badge/skills/hackermanishackerman/claude-skills-vault/toon.svg" alt="Measured on agentmods" height="20"></a>
Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,692 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin 100% copy Near-identical to another mod 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 5.1 $0.00044 $0.01692
Opus 5 $0.00022 $0.00846
Sonnet 5 $0.00009 $0.00338
Haiku 4.5 $0.00004 $0.00169

Measured 8d ago against content hash 359773d5500d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

toon 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 8d ago.

The scan reads SKILL.md. This mod also ships 3 executable files (scripts/convert.js, scripts/convert.py, scripts/validate.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.

Origin

This is a copy

100% identical to toon — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.claude/skills/document-skills/toon/SKILL.md · 251 lines

How it starts

The opening of the file, as written. The whole thing — 251 lines — stays where its author put it; the contents beside it link to each section on GitHub.

TOON Format Guide

Overview

TOON (Token-Oriented Object Notation) is a compact encoding of JSON designed for LLM input. Combines YAML-style indentation w/ CSV-style tables for uniform arrays.

Key benefits:

  • ~40% fewer tokens vs JSON
  • 73.9% accuracy vs 69.7% for JSON in retrieval tasks
  • Explicit length declarations for validation
  • Lossless JSON round-trips

Syntax

Objects (YAML-style indentation)

user:
  name: John
  age: 30
  address:
    city: NYC
    zip: 10001

Uniform Arrays (Tabular)

users[3]{id,name,email}:
  1,John,[email protected]
  2,Jane,[email protected]
  3,Bob,[email protected]
  • [N] = array length (req for validation)
  • {fields} = column schema (declared once)

Scalar Arrays

tags[4]: api,rest,json,toon

Non-uniform Arrays (Nested)

items:
  - id: 1
    type: book
    meta:
      pages: 200
  - id: 2
    type: video
    meta:
      duration: 3600

Conversion Rules

JSON to TOON

  1. Objects => indented key-value pairs
  2. Uniform arrays => tabular [N]{fields}: format
  3. Mixed/nested arrays => - list notation
  4. Scalars => quote only when containing , or special chars

Examples

JSON:

{"orders":[{"id":1,"item":"Book","qty":2,"price":29.99},{"id":2,"item":"Pen","qty":10,"price":1.99}]}

TOON:

orders[2]{id,item,qty,price}:
  1,Book,2,29.99
  2,Pen,10,1.99

Nested JSON:

{"config":{"db":{"host":"localhost","port":5432},"cache":{"enabled":true,"ttl":300}}}

TOON:

config:
  db:
    host: localhost
    port: 5432
  cache:
    enabled: true
    ttl: 300

When to Use TOON

TOON replaces data serialization formats when sending to LLMs.

Formats to convert → TOON:

Format Convert? Notes
JSON Yes Primary use case
JSON compact Yes Same as JSON
YAML Yes Structured data
XML Yes Verbose, big savings

Read the full file on GitHub · 251 lines

Files

What ships with it

7 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. 8d ago First seen · 251 lines · 44 tokens per session scan A 359773d5500d

Subscribe to this mod's changes

toon is a skill published in the GitHub repository hackermanishackerman/claude-skills-vault (2 stars, last pushed yesterday), licensed MIT. It adds 44 tokens to every session and 1,692 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to toon, differing in 0 lines, and is treated as a copy.

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