Automated summary

Converts structured data files (JSON, YAML, CSV) into token-efficient formats to reduce token usage in LLM contexts.

Strengths

Reduces tokens by 30-70% on structured data
Supports multiple input formats (JSON, YAML, XML, CSV)
Offers filtering, truncation, and format selection options

Limitations

May lose some nested structure details if truncation is too aggressive
Best for tabular or uniform data sets
Not suitable if full data fidelity is required without any loss

When to use it

When feeding large structured data into an LLM and aiming to minimize token costs.

When not to use it

If you need to preserve the complete original data structure with no information loss.

Security analysis

Safe

Quality score90/100

The skill is a data formatting utility that converts structured formats (JSON/YAML/XML/CSV) into token-efficient representations. It does not execute any destructive operations, exfiltrate data, or disable safety features. All actions are legitimate transformations, and no risky patterns like curl-pipe-shell or unexpected system modifications are present.

No concerns found

How this analysis is made

Examples

Basic conversion to TOON

Convert this JSON file to TOON format to save tokens: llm-fmt data.json

CSV to TSV for maximum savings

I have a large CSV file, convert it to TSV format for token efficiency: llm-fmt data.csv -f tsv

Analyze best format

Analyze the best format for my JSON data: llm-fmt data.json --analyze

name: llm-fmt description: Convert JSON/YAML/XML/CSV to token-efficient formats (30-70% savings) allowed-tools: Bash

llm-fmt

Name: llm-fmt - Token optimization for structured data
Author: Skills Guide Bot

Reduces tokens by 30-70% for structured data in LLM contexts.

Usage

llm-fmt data.json                    # TOON output (default)
llm-fmt data.json -f tsv             # TSV (best for tables, 60-75% savings)
llm-fmt data.json -f yaml            # YAML (nested configs, 25-35%)
llm-fmt data.json --analyze          # Compare all formats

Filtering & Truncation

llm-fmt data.json -i "users[*].name"           # Extract paths
llm-fmt data.json --max-depth 3                # Limit nesting
llm-fmt data.json --max-items 50               # Limit arrays
llm-fmt data.json --max-string-length 200      # Limit strings
llm-fmt data.json --truncation-strategy tail   # head|tail|balanced|sample

Format Guide

| Data | Format | Savings | |------|--------|---------| | Tables, uniform arrays | tsv | 60-75% | | Object arrays (API/logs) | toon | 45-60% | | Nested configs | yaml | 25-35% | | Mixed/complex | json | 10-15% |

Pipes

curl -s api.example.com/data | llm-fmt -f tsv
cat large.json | llm-fmt --max-items 100

From the file to a first result

The download contains exactly the content displayed on this page. This copy may differ from the latest version in the source repository.

View the source and supporting files

This download contains SKILL.md only. Any scripts, references, templates and dependencies are not included. Get the required files from the source, preserving their directory structure, before continuing.

1. Download the file

Download SKILL.md

From the root of a test project, save the file as .skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht/SKILL.md, or use the command below. This folder is for inspecting the skill before installation.

Command for macOS/Linux or WSL: requires a POSIX shell and curl. On Windows without WSL, use the download button and create the folder manually.

mkdir -p '.skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht' && curl --fail --show-error --location 'https://skills-guides.com/api/skills/llm-fmt-token-optimization-for-structured-data-mm5t8aht/download' --output '.skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht/SKILL.md.part' && mv '.skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht/SKILL.md.part' '.skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht/SKILL.md'

2. Check prerequisites

Read SKILL.md before using it. If it references scripts or external services, inspect them and prepare the required access in your test environment.

Tools declared by the author (check availability in your agent): Bash

No recognized prerequisites section in this file. This does not mean it is self-contained: libraries, tools and access requirements may be mentioned elsewhere in the content or source repository.

The platforms on this page are catalog indications. The paths below follow tool documentation; they do not prove this skill has been run in those tools. No minimum tool version is confirmed for this listing.

3. Load the skill

After inspection, copy the complete folder into your project using one of the commands below, then open a new tool session. The command stops if a folder with the same name already exists: compare the files before replacing it.

Claude Code

test -f '.skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht/SKILL.md' && test -s '.skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht/SKILL.md' && mkdir -p '.claude/skills' && test ! -e '.claude/skills/llm-fmt' && cp -R '.skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht' '.claude/skills/llm-fmt'

Cursor

test -f '.skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht/SKILL.md' && test -s '.skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht/SKILL.md' && mkdir -p '.cursor/skills' && test ! -e '.cursor/skills/llm-fmt' && cp -R '.skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht' '.cursor/skills/llm-fmt'

Codex

test -f '.skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht/SKILL.md' && test -s '.skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht/SKILL.md' && mkdir -p '.agents/skills' && test ! -e '.agents/skills/llm-fmt' && cp -R '.skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht' '.agents/skills/llm-fmt'

OpenSkills

OpenSkills must already be installed. The local install/read procedure is checked with OpenSkills 1.5.0, which requires Node.js ≥ 20.6.0. Catalog slugs are not resolved automatically.

Official OpenSkills installation

openskills install './.skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht'

openskills read 'llm-fmt-token-optimization-for-structured-data-mm5t8aht'

Reading should display the installed file content and its base directory. It does not run the skill or install its dependencies.

For an agent that reads AGENTS.md, then sync the index. This command changes AGENTS.md: review the diff before using it.

openskills sync

Manual method or another tool: attach SKILL.md to a conversation, or open it in an agent that can read files. Include any required supporting resources. No universal folder is recognized by every tool.

4. Try a first task

Use a short, synthetic input: an API endpoint, a small document or an interface brief. In a new conversation, attach the file or give the agent its path, then adapt this request:

Read .skill-downloads/llm-fmt-token-optimization-for-structured-data-mm5t8aht/SKILL.md and apply its instructions to this example: [describe a test input]. Identify any missing files, dependencies or access. Produce the result requested by the skill without inventing data or running unreviewed scripts.

Expected result: output matching the skill instructions, or a precise list of missing prerequisites. A read confirmation alone does not validate a first use. If an external resource is unavailable, that path remains untested.

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