---

name: grammar-checker description: Check grammar, spelling, and punctuation in written content. Identify common errors and provide corrections. Use when reviewing any written content for grammatical accuracy.

Grammar Checker

Goal: Ensure content is free from grammar, spelling, and punctuation errors.

---

1. Common Grammar Errors

English Common Errors

Error Type	Incorrect	Correct
Subject-Verb Agreement	The team are ready	The team is ready
Tense Consistency	I walked and talk	I walked and talked
Article Usage	I have apple	I have an apple
Run-on Sentences	I went home I was tired	I went home**;** I was tired
Comma Splice	It's hot, I'm sweating	It's hot**,** so I'm sweating

Commonly Confused Words

Words	Difference
affect / effect	affect (v.) to influence; effect (n.) result
their / there / they're	their = possessive; there = location; they're = they are
its / it's	its = possessive; it's = it is
your / you're	your = possessive; you're = you are
then / than	then = next; than = comparison

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2. Spelling Check

Commonly Misspelled Words

accommodate ≠ accomodate
definitely ≠ definately
occurrence ≠ occurence
separate ≠ seperate
necessary ≠ neccessary
receive ≠ recieve

Homophones

Words	Context
to / too / two	to = direction; too = also/excessive; two = number
accept / except	accept = agree; except = exclude
principal / principle	principal = main/head; principle = rule/belief
complement / compliment	complement = complete; compliment = praise

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3. Punctuation Rules

English Punctuation

## Common Rules

1. Period (.) - End of declarative sentence
2. Comma (,) - Separating clauses, lists, introductory elements
3. Semicolon (;) - Connecting related independent clauses
4. Colon (:) - Introducing lists or explanations
5. Apostrophe (') - Possession, contractions
6. Quotation marks ("") - Direct speech, titles of short works
7. Hyphen (-) - Compound words (well-known)
8. En dash (–) - Ranges (pages 10–15)
9. Em dash (—) - Interruption, emphasis, parenthetical

## Key Rules

- Use Oxford comma in lists of three or more
- Place periods and commas inside quotation marks
- No space before punctuation marks
- One space after punctuation marks

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4. Checklist

## Grammar Check Checklist

### Basic Checks
- [ ] No spelling errors
- [ ] Punctuation used correctly
- [ ] Complete sentence structure
- [ ] Subject-verb agreement

### Advanced Checks
- [ ] Consistent verb tenses
- [ ] Correct word order
- [ ] Proper collocations
- [ ] No redundant expressions

### Formatting Checks
- [ ] Consistent punctuation style
- [ ] Uniform number formats
- [ ] Proper nouns capitalized correctly

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5. Common Fix Patterns

Fix Template

## Issue: [Error Type]

**Original**: [Incorrect content]
**Problem**: [Description of the issue]
**Correction**: [Fixed content]
**Rule**: [Applicable rule]

Examples

## Issue: Subject-Verb Agreement

**Original**: The list of items are on the table.
**Problem**: "list" is the subject (singular), not "items"
**Correction**: The list of items **is** on the table.
**Rule**: Subject-verb agreement with prepositional phrases

## Issue: Dangling Modifier

**Original**: Walking to school, the rain started.
**Problem**: The modifier "Walking to school" has no proper subject
**Correction**: Walking to school, **I** got caught in the rain.
**Rule**: Modifiers must clearly refer to the subject of the sentence

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Quick Reference

Verb Tense Quick Guide

Tense	Structure	Example
Simple Present	V / V-s	I write
Simple Past	V-ed	I wrote
Present Perfect	have/has + V-ed	I have written
Past Perfect	had + V-ed	I had written
Future	will + V	I will write
Present Continuous	am/is/are + V-ing	I am writing

Common Rules at a Glance

1. a → before consonant sounds (a book, a university)
2. an → before vowel sounds (an apple, an hour)
3. Comma after introductory clauses
4. No comma before "that" in restrictive clauses
5. Use "who" for people, "which/that" for things

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Integration with auto-writer

## When to Invoke

- After each writing iteration
- As a core validation step

## Output Format

{
  "hasErrors": boolean,
  "errorCount": number,
  "errors": [
    {
      "type": "spelling|grammar|punctuation",
      "original": "incorrect content",
      "suggestion": "suggested fix",
      "position": "position description"
    }
  ]
}