WSC Writing Style Checker

CI npm smithery badge wsc MCP server 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

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.

{
  "$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.

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

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

.
├── 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

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

License

MIT