Readability

Takes your text and runs it through multiple readability formulas at once: Flesch Reading Ease, Flesch-Kincaid Grade Level, Gunning Fog, and SMOG. You get actual scores with interpretation, plus statistics like word count, sentence length, and complex word percentage. Handy when you're writing documentation, marketing copy, or anything where reading level matters and you want objective numbers instead of guessing. The output includes specific recommendations like which sentences to shorten or complex words to simplify. Better than running text through four different calculators separately, and the interpretation guide helps you understand what a Flesch score of 65 actually means for your audience.

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skills.sh installs: 589
GitHub stars: 55
last updated: Aug 21, 2026

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Install

$ npx -y skills add humanizerai/agent-skills --skill readability --agent claude-code

Installs into .claude/skills of the current project.

Files

Analyze Readability

Calculate and display readability metrics for the provided text.

Input

The user provides text in $ARGUMENTS. If no text provided, ask for it.

Metrics to Calculate

Core Scores

Metric	Formula	Interpretation
Flesch Reading Ease	206.835 - 1.015(words/sentences) - 84.6(syllables/words)	0-100, higher = easier
Flesch-Kincaid Grade	0.39(words/sentences) + 11.8(syllables/words) - 15.59	US grade level
Gunning Fog Index	0.4[(words/sentences) + 100(complex words/words)]	Years of education
SMOG Index	1.043 × √(complex words × 30/sentences) + 3.1291	Grade level

Complex words = 3+ syllables

Text Statistics

Word count
Sentence count
Average sentence length (words)
Average word length (characters)
Complex words count and %
Passive voice sentences (estimate)

Output Format

## Readability Analysis

### Scores
| Metric | Score | Meaning |
|--------|-------|---------|
| Flesch Reading Ease | [X] | [interpretation] |
| Flesch-Kincaid Grade | [X] | [grade level] |
| Gunning Fog | [X] | [years education] |
| SMOG | [X] | [grade level] |

SKILL.md on GitHub