tuyv TOON v2.0 Formatter
Use TOON when it materially reduces prompt size without making the payload harder to inspect or validate. It is strongest for large, mostly uniform arrays and weakest for small, nested, or irregular data.
When to Use
YES - Use automatically:
- Arrays with ≥5 similar items
- Tables, logs, events, transactions, analytics
- API responses with ≥60% field uniformity
- Database results, metrics, benchmarks
NO - Keep as JSON:
- Small arrays (<5 items)
- Deeply nested or non-uniform data
- Narrative text, instructions
Quick Reference
Tabular (uniform objects):
[3]{id,name,role}:
1,Alice,admin
2,Bob,user
3,Carol,user
Inline (primitives ≤10):
tags[4]: js,react,node,api
Delimiters: comma (default), tab [N\t], pipe [N|]
Key folding (nested objects):
server.host: localhost
server.port: 8080
Runtime Options
# Claude installs include slash commands that call this wrapper:
node .claude/utils/toon/cli.mjs encode data.json
# With options:
node .claude/utils/toon/cli.mjs encode data.json --delimiter tab --no-key-folding
# Compare token savings:
node .claude/utils/toon/cli.mjs analyze data.json
# Decode TOON to JSON:
node .claude/utils/toon/cli.mjs decode data.toon
If the wrapper or slash commands are not installed in the target project, use an available @toon-format/toon CLI/library or convert manually from the spec and validate the result.
Commands
/toon-encode <file>- JSON to TOON/toon-decode <file>- TOON to JSON/toon-validate <file>- Validate TOON/analyze-tokens <file>- Compare savings/convert-to-toon <file>- Full conversion workflow
Documentation
- Guide:
references/toon-guide.md - Spec: https://github.com/toon-format/spec