toon-skill

toon-skill

A Claude skill that compresses large, heavy prompts into lean, unambiguous specs for AI coding agents — encoding any structured data inside the prompt as TOON (Token-Oriented Object Notation) to cut token usage.

Triggered by starting a message with /toon, or by asking to compress/optimize/reduce the token cost of a prompt headed for a coding agent (Claude Code, Cursor, Copilot, Antigravity, OpenCode, Windsurf, etc.).

What it does

Heavy prompts are usually two things tangled together, and this skill treats them differently:

• Prose (instructions, context, requirements) is rewritten tighter — filler and hedging cut, exact file paths / constraints / done-criteria always preserved — so the result is still safe for an autonomous agent to act on without asking a follow-up question.
• Structured data (file lists, test cases, config, sample records) is re-encoded in TOON, which benchmarks ~30–60% fewer tokens than pretty-printed JSON on uniform, tabular data.

It also knows when not to use TOON — deeply nested or non-uniform data, or a handful of key-value pairs, are left as compact JSON, since TOON's savings only materialize on uniform tabular arrays.

See SKILL.md for the full workflow and references/ for the TOON syntax cheat sheet and the prompt-compression rules.

Install

Requires Python 3. The bundled converter (scripts/to_toon.py) prefers the official @toon-format/cli via npx (Node.js) when available, and falls back to a bundled pure-Python encoder otherwise.

git clone https://github.com/sheikhsajid69/toon-skill.git
cd toon-skill
./install.sh              # personal install: ~/.claude/skills/toon — available in every project
./install.sh --project    # this repo only: ./.claude/skills/toon — commit it to share with a team

Claude Code / Claude Desktop

install.sh drops the skill straight into the directory these tools already scan (~/.claude/skills/ or <project>/.claude/skills/). No further setup — the skill triggers automatically once the agent's task matches its description.

Claude.ai (web/desktop/mobile)

Zip the folder (SKILL.md, references/, scripts/) into a .skill file and upload it from Settings → Capabilities → Skills.

Other IDE agents (Cursor, Windsurf, Copilot Chat, etc.)

These tools don't read a skills/ folder natively. Point the agent's custom-instructions / rules file at the installed SKILL.md, e.g. in .cursor/rules or your agent's system-prompt config:

Follow the workflow in ~/.claude/skills/toon/SKILL.md whenever asked to
compress, optimize, or /toon a prompt.

Usage

/toon <paste your heavy prompt here>

or just ask directly: "toonify this prompt for my coding agent", "compress this so it costs fewer tokens".

The converter script can also be run standalone:

python3 scripts/to_toon.py input.json --stats

Repo structure

toon-skill/
├── SKILL.md                            # workflow the agent follows
├── references/
│   ├── toon-cheatsheet.md              # TOON syntax + tabular-eligibility check
│   └── prompt-compression-guide.md     # what to cut vs. never cut, worked example
├── scripts/
│   └── to_toon.py                      # JSON -> TOON converter (CLI-backed, Python fallback)
├── install.sh
├── LICENSE
└── SECURITY.md

Testing

Run the test suite:

pytest tests/

License

MIT