Writing Style Checker

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

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.

config.json

{
  "$schema": "https://wsc.theserverless.dev/schema.json",
  "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.

API Usage

`POST /api/check`

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

Terminal

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

Response:

config.json

{
  "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:

Terminal

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.

config.json

{
  "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.

Terminal

npx wsc-mcp

Claude Desktop / Claude Code config:

config.json

{
  "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.

bash

# 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

yaml

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

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`	Only check files changed in this PR

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

Code

.
├── 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

bash

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.

Terminal

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

Matt Might for the original shell scripts
Built with SvelteKit and Svelte 5, deployed on Cloudflare Workers
Logo made with DiffusionBee

License

MIT