toon-formatter

name	toon-formatter
description	Compress and format structured data with TOON to cut prompt size without losing shape. Use for JSON, tables, logs, API responses, or repeated records when token budget matters.
disable-model-invocation	true
user-invocable	true

TOON Formatter

Use TOON for structured data when you want JSON-level fidelity with fewer tokens. It works best for repeated records, tables, logs, metrics, and API responses. Expect roughly 30-60% savings on regular data.

Use TOON When

• Arrays have at least 5 similar items.
• Objects mostly share the same keys.
• Shape matters more than JSON punctuation.
• You want compact data in prompts, summaries, or agent handoffs.

Keep JSON When

• Arrays are tiny.
• Data is deeply nested or irregular.
• Another tool must consume JSON directly.
• The output is prose, instructions, or a one-off example.

Fastest Workflow

If the toon CLI is available, pipe structured output through it:

curl -s "https://api.example.com/data" | toon
cat data.json | toon
some_command | toon

toon is safe on non-JSON output and passes it through unchanged.

If you need a local file converter in this repo, use:

python3 claude/skills/toon-formatter/toon-convert.py input.json -o output.toon
python3 claude/skills/toon-formatter/toon-convert.py data.json --delimiter tab

Manual Formatting Rules

1. Pick the right array form

• Inline for short primitive arrays: tags[3]: alpha,beta,gamma

• Tabular for regular objects:

  [2]{id,name}:
    1,Alice
    2,Bob
  

• List form for mixed or irregular items:

  [2]:
    - name: Alice
      role: admin
    - error: timeout
  

2. Pick the delimiter

• Comma: default and most compact
• Tab: better when values contain commas
• Pipe: useful when you want markdown-like rows

3. Keep explanations short

State the format choice once, then show the data:

Using TOON for 150 user records (uniform shape, lower token cost).

Examples

API response

[2]{id,name,email}:
  1,Alice,[e-mail]
  2,Bob,[e-mail]

Nested keys with folding

server.host: localhost
server.port: 8080
database.host: db.example.com

Install

The standalone CLI is @toon-format/cli.

References

• Spec: https://github.com/toon-format/spec
• Format site: https://toonformat.dev
• Local converter: claude/skills/toon-formatter/toon-convert.py