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WSC - Writing Style Checker

WSC - Writing Style Checker

Writing Style Checker

CI npm wsc MCP server M8ven Score License: MIT

A prose linter and AI-slop detector. WSC finds AI tells — words, phrases, and sentence structures overrepresented in AI-generated text, each flag backed by a published corpus study. It also catches classic writing issues: weasel words, passive voice, duplicate words, long sentences, nominalizations, hedging, and filler adverbs. Available as a web editor, HTTP API, MCP server, CLI, and GitHub Action.

Live: wsc.theserverless.dev

Screenshot of Writing Style Checker

Features

  • Web Editor - Real-time highlighting with inline fix buttons for all 8 detectors

  • HTTP API - POST text with optional config, retrieve structured JSON responses

  • MCP Server (Remote) - Connect AI assistants via Streamable HTTP transport

  • MCP Server (Local) - Stdio-based server via wsc-mcp on npm

  • CLI - Check files from the command line via wsc-lint

  • GitHub Action - Run checks in CI with ::warning annotations

  • Configurable - Customize detectors with .wscrc.json files


Related MCP server: TrueVoice MCP

What WSC is (and isn't)

WSC flags patterns that research on AI-generated text finds overrepresented, and cites a source for every flag. It does not, and cannot, prove authorship. Classifier-based detectors carry a documented false-accusation risk: a Stanford study found that seven of them misflagged 61% of essays written by non-native English speakers. WSC avoids that trap by design — every flag is a specific, explainable edit that improves the text no matter who, or what, wrote it.


Detection Rules

Detector

Items

Description

Weasel Words

95 words/phrases

Vague terms like "very", "basically", "arguably", "numerous"

Passive Voice

260 irregular verbs

Auxiliary verbs + past participles (regular -ed + irregular)

Duplicate Words

—

Adjacent repeated words across whitespace, case-insensitive

Long Sentences

threshold: 30 words

Sentences exceeding a configurable word count

Nominalizations

245 word pairs

Nouns replaceable with verbs ("utilization" → "use")

Hedging

100 phrases

Phrases that weaken assertions ("I think", "it seems")

Filler Adverbs

139 words

Adverbs adding emphasis without substance ("totally", "utterly")

AI Tells

98 words (+111 inflected forms) + 83 phrases + 12 structural patterns

Words, phrases, and sentence constructions overrepresented in AI-generated text (delve, rich tapestry, It's not just X — it's Y)

Word lists sourced from Matt Might's shell scripts and expanded with additional entries. AI tells draw on published corpus studies: Kobak et al. 2025 (Science Advances), Juzek & Ward 2025 (COLING), Liang et al. 2024 (Stanford), and Reinhart et al. 2025 (PNAS). Wikipedia's editor-maintained Signs of AI writing catalogue and AI-detection vendor reports round out the sources.


Configuration

Create a .wscrc.json to customize detectors. All tools (API, MCP, CLI) support it.

{
  "$schema": "https://wsc.theserverless.dev/schema.json",
  "ignore": ["CHANGELOG.md", "docs/vendor/**"],
  "detectors": {
    "weaselWords": {
      "enabled": true,
      "add": ["synergy", "leverage"],
      "remove": ["very"]
    },
    "longSentences": { "maxWords": 25 },
    "adverbs": { "enabled": false }
  }
}

Every field is optional. Missing fields use defaults. JSON Schema provides autocompletion in VS Code.

ignore is an array of glob patterns relative to the working directory. The GitHub Action uses the repository root. The CLI adds these patterns to its built-in **/node_modules/** and **/.git/** skips, together with the Action exclude input and the CLI --ignore flag.


API Usage

POST /api/check

Analyze text for writing style issues. Accepts optional config object.

curl -X POST https://wsc.theserverless.dev/api/check \
  -H "Content-Type: application/json" \
  -d '{"text":"The code was written very quickly."}'

Response:

{
  "summary": {
    "total": 2,
    "weaselWords": 1,
    "passiveVoice": 1,
    "duplicateWords": 0,
    "longSentences": 0,
    "nominalizations": 0,
    "hedging": 0,
    "adverbs": 0
  },
  "issues": {
    "weaselWords": [{ "word": "very", "index": 21, "line": 1, "column": 22, "context": "..." }],
    "passiveVoice": [{ "phrase": "was written", "index": 9, "line": 1, "column": 10, "context": "..." }],
    "duplicateWords": [],
    "longSentences": [],
    "nominalizations": [],
    "hedging": [],
    "adverbs": []
  },
  "meta": { "characterCount": 34, "wordCount": 6, "sentenceCount": 1, "processingTimeMs": 2 }
}

With config:

curl -X POST https://wsc.theserverless.dev/api/check \
  -H "Content-Type: application/json" \
  -d '{"text":"The code was written very quickly.", "config":{"detectors":{"weaselWords":{"enabled":false}}}}'

GET /api/check

Returns API documentation as JSON.

GET /api/detectors

Returns the list of all 8 detectors with descriptions, configurability, and word counts.

GET /health

Runs a smoke test with known text and returns {"status":"healthy"} or 503.

Limits: Max 100,000 characters per request. CORS enabled for all origins.


MCP Server

The Writing Style Checker is available as an MCP server, letting AI assistants check your writing directly.

Tools

Tool

Description

check_text

Analyze text for all 8 writing style issues. Accepts optional config.

fix_duplicates

Remove duplicate adjacent words and return cleaned text

list_word_lists

Return info about all detector word lists

check_file

(Local only) Read a file from disk and analyze it. Auto-discovers .wscrc.json.

Remote MCP Server

Connect any MCP client to the hosted server - no installation required.

{
  "mcpServers": {
    "writing-style-checker": {
      "type": "url",
      "url": "https://wsc.theserverless.dev/mcp"
    }
  }
}

Local MCP Server (stdio)

Install via npm for local usage. Includes check_file for analyzing files on disk with auto-discovery of .wscrc.json.

npx wsc-mcp

Claude Desktop / Claude Code config:

{
  "mcpServers": {
    "writing-style-checker": {
      "command": "npx",
      "args": ["wsc-mcp"]
    }
  }
}

See the wsc-mcp npm page for full documentation.


CLI

Check files from the command line.

# Check all markdown files
npx wsc-lint check "**/*.md"

# Read from stdin
echo "The code was written very quickly." | npx wsc-lint check --stdin

# JSON output for scripting
npx wsc-lint check "**/*.md" --format json

# GitHub Actions annotations
npx wsc-lint check "**/*.md" --format github

# Create a config file
npx wsc-lint init

See the wsc-lint README for full documentation.


GitHub Action

- uses: theserverlessdev/wsc@v1
  with:
    files: '**/*.md'
    max-warnings: 20
    exclude: |
      CHANGELOG.md
      vendor/**

Input

Default

Description

files

**/*.md

Glob pattern for files to check

config

—

Path to .wscrc.json config file

max-warnings

unlimited

Max warnings before failing

only-changed

false

On a pull request, check changed files that match files. If none match, skip the check. Other events check files.

exclude

—

Glob patterns to skip. Separate with a comma or a new line. Adds to config ignore.


Privacy

The web editor runs in your browser - we never send text to any server. The API and MCP endpoints only process text you explicitly send to them.


Project Structure

.
├── src/
│   ├── core/                    # Shared detection engine
│   │   ├── detector.ts          # 8 detection algorithms
│   │   ├── words.ts             # Word/phrase lists (800+ entries)
│   │   ├── config.ts            # Config types, merging, validation
│   │   ├── config-node.ts       # Node-only: file loading, discovery
│   │   ├── analyzer.ts          # Unified analyzeText() entry point
│   │   └── index.ts             # Public API exports
│   ├── docs/                    # Documentation content (Markdown files)
│   ├── mcp/
│   │   └── handler.ts           # MCP JSON-RPC 2.0 handler
│   ├── lib/
│   │   ├── App.svelte           # Main editor page component
│   │   ├── stores/theme.ts      # Theme store (light/dark/system)
│   │   └── components/          # UI components (StatsBar, ConfigPanel, etc.)
│   ├── routes/
│   │   ├── +layout.svelte       # Shared layout (header, nav, footer)
│   │   ├── api/check/+server.ts # HTTP API endpoint
│   │   ├── mcp/+server.ts       # MCP endpoint
│   │   ├── health/+server.ts    # Health check endpoint
│   │   ├── docs/+page.svelte    # Documentation page
│   │   └── words/+page.svelte   # Word library browser
│   └── styles/
│       └── main.scss            # Global styles (light + dark themes)
├── mcp-server/                  # Standalone stdio MCP server (npm: wsc-mcp)
├── cli/                         # CLI tool (npm: wsc-lint)
├── action/                      # GitHub Action (composite)
├── tests/                       # 341 tests across 18 files
├── static/
│   ├── schema.json              # JSON Schema for .wscrc.json
│   ├── llms.txt                 # AI/LLM discovery file
│   └── llms-full.txt            # Detailed LLM context
├── wrangler.toml                # Cloudflare Workers config
└── svelte.config.js             # SvelteKit configuration

Local Development

git clone https://github.com/theserverlessdev/wsc.git
cd wsc
npm install
npm run dev

Visit http://localhost:5173. The API is at /api/check, MCP at /mcp, health at /health.

Commands

Command

Description

npm run dev

Start dev server

npm run build

Build for production

npm run check

Type check with svelte-check

npm test

Run all 341 tests

npm run test:coverage

Coverage report

Deployment

Deployed as a Cloudflare Worker at wsc.theserverless.dev.

npm run build
npx wrangler deploy

Contributing

See CONTRIBUTING.md for development setup, testing, and pull request guidelines.

For substantial changes, please open an issue first.

Acknowledgements

License

MIT

Available Tools

4 tools
check_fileCheck a file for writing style issuesA
Read-only
Inspect

Read a UTF-8 file from local disk and analyze it for the same writing style issues as check_text (weasel words, passive voice, hedging, AI tells, and more). Read-only: the file is never modified, and Markdown files are automatically masked so code blocks and tables are not linted as prose. A .wscrc.json config is auto-discovered from the file's directory upward unless config is passed explicitly. Returns the same line-and-column report as check_text, or an error message for unreadable or oversized (over 100,000 characters) files. Use when the text lives on disk; use check_text for text already in the conversation.

Inputs: path (required), config.

check_textCheck text for writing style issuesA
Read-only
Inspect

Analyze text for writing style issues: weasel words, passive voice, duplicate words, long sentences, nominalizations, hedging, filler adverbs, and research-cited AI tells. Read-only and stateless — text is analyzed in memory, never stored. Returns a plain-text report with each issue's line and column, the matched text, surrounding context, and the reason for AI tells; texts over 100,000 characters return an error message. Use this for text already in the conversation; use check_file for files on disk. It only reports issues — to auto-remove duplicate words, follow up with fix_duplicates.

Inputs: text (required), config, format.

fix_duplicatesRemove duplicate adjacent wordsA
Read-only
Inspect

Remove duplicate adjacent words (case-insensitive, including across line breaks) and return the cleaned text plus the list of words that were removed. Read-only with no side effects: the fix is returned in the response, nothing is written anywhere. Use after check_text or check_file reports duplicate words; other issue types are report-only and have no auto-fix.

Inputs: text (required).

list_word_listsList detector word listsA
Read-only
Inspect

Return every detector word/phrase list with its entry count, config key, and sample entries, plus a link to the full browsable library. Read-only, takes no parameters, and returns the same catalog for a given release. Use it to see what the detectors match before tuning a config for check_text or check_file; not needed for ordinary checking.

Inputs: no named parameters.

Tool Schema Changelog

Recent tool additions, removals, and schema changes observed during successful MCP inspections.

Loading tool schema changelog…

    TDQS

    A4.7/5.0

    Scored across 4 tools

    Disambiguation5/5

    Each tool has a clearly distinct purpose: check_file vs check_text differ by input source, fix_duplicates is for fixing a specific issue, and list_word_lists provides reference data. No overlap in functionality.

    Naming Consistency5/5

    All tool names follow a consistent verb_noun pattern in snake_case (check_file, check_text, fix_duplicates, list_word_lists), making the API predictable.

    Tool Count5/5

    With 4 tools, the server is well-scoped for a writing style checker: two input methods for analysis, one fix action, and one list action. Not overly sparse or heavy.

    Completeness4/5

    The tool surface covers core checking and duplicate removal, but lacks auto-fix for other issue types (e.g., weasel words, passive voice). Users must manually edit text after reports, which is a minor gap.

    Maintenance

    ActivityNo data
    ResponsivenessOutdated data

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