StyleMCP

Executable brand rules for AI models and agents. Keep every AI-generated message on-brand.

What is StyleMCP?

StyleMCP validates and rewrites AI-generated text to match your brand voice. Use it as:

• REST API - Validate text from any application
• MCP Server - Direct integration with Claude and other AI agents
• CLI - Check copy in your terminal or CI/CD
• GitHub Action - Catch off-brand copy in pull requests

Quick Start

API

curl -X POST https://stylemcp.com/api/validate \
  -H "Content-Type: application/json" \
  -d '{"text": "Click here to learn more!"}'

Response:

{
  "valid": false,
  "score": 65,
  "issues": [
    {
      "rule": "no-click-here",
      "message": "Avoid 'click here' - describe the destination instead",
      "suggestion": "Learn more about our features"
    }
  ]
}

CLI

# Install
npm install -g stylemcp

# Validate text
stylemcp validate "Click here to learn more"

# Validate file
stylemcp validate src/copy/homepage.json --pack saas

# Rewrite text
stylemcp rewrite "Please utilize our product" --mode aggressive

MCP (Claude Desktop)

Add to your claude_desktop_config.json:

{
  "mcpServers": {
    "stylemcp": {
      "command": "npx",
      "args": ["stylemcp"]
    }
  }
}

Now Claude can validate and rewrite text using your brand rules.

API Endpoints

| Method | Endpoint | Description | |--------|----------|-------------| | POST | /api/validate | Validate text against brand rules | | POST | /api/rewrite | Rewrite text to match brand voice | | POST | /api/validate/batch | Validate multiple texts | | GET | /api/packs | List available style packs | | GET | /api/packs/{pack}/voice | Get voice guidelines | | GET | /api/packs/{pack}/ctas | Get CTA rules | | GET | /api/mcp/sse | MCP SSE endpoint | | POST | /api/mcp/call | MCP tool calls |

Style Packs

StyleMCP uses style packs - YAML files that define your brand rules.

Default Pack: saas

The included saas pack is designed for B2B SaaS products:

• Vocabulary: Prefer "use" over "utilize", "help" over "assist"
• Forbidden words: "synergy", "leverage", "cutting-edge", "game-changing"
• Patterns to avoid: "click here", "we're sorry for any inconvenience"
• CTA rules: Avoid "Submit", "Click here", "OK" - prefer "Save", "Create", "Sign up"

Pack Structure

packs/
  my-brand/
    manifest.yaml      # Pack metadata
    voice.yaml         # Tone, vocabulary, forbidden words
    copy_patterns.yaml # Reusable copy templates
    cta_rules.yaml     # Button/CTA guidelines
    tokens.json        # Design tokens (optional)

Create Your Own Pack

# Copy the default pack
cp -r packs/saas packs/my-brand

# Edit the rules
nano packs/my-brand/voice.yaml

# Use your pack
curl -X POST https://stylemcp.com/api/validate \
  -d '{"text": "Your text", "pack": "my-brand"}'

voice.yaml Example

tone:
  summary: "Friendly, clear, and helpful"
  attributes:
    - name: friendly
      weight: 0.8
    - name: professional
      weight: 0.7

vocabulary:
  rules:
    - preferred: "use"
      avoid: ["utilize", "leverage"]
    - preferred: "help"
      avoid: ["assist", "facilitate"]

  forbidden:
    - "synergy"
    - "paradigm shift"
    - "game-changing"

doNot:
  - pattern: "click here"
    reason: "Poor accessibility"
    suggestion: "Describe the destination"
    severity: error

  - pattern: "\\b(obviously|simply|just)\\b"
    isRegex: true
    reason: "Can make users feel stupid"
    severity: warning

Self-Hosting

Docker

# Clone the repo
git clone https://github.com/stylemcp/stylemcp.git
cd stylemcp

# Set up environment
echo "STYLEMCP_API_KEY=$(openssl rand -hex 32)" > .env

# Run with Docker
docker compose up -d

# Check health
curl http://localhost:3000/health

Manual

# Install dependencies
npm install

# Build
npm run build

# Start server
npm start

GitHub Actions

name: Brand Check
on: [pull_request]

jobs:
  validate:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Validate copy
        run: |
          npx stylemcp validate src/copy/*.json \
            --min-score 80 \
            --format github

Environment Variables

| Variable | Description | Default | |----------|-------------|---------| | PORT | Server port | 3000 | | STYLEMCP_API_KEY | API key for authentication | (none) | | GITHUB_WEBHOOK_SECRET | GitHub webhook secret | (none) |

MCP Tools

When used as an MCP server, StyleMCP provides these tools:

| Tool | Description | |------|-------------| | validate_text | Validate text against brand rules | | rewrite_to_style | Rewrite text to match brand voice | | get_voice_rules | Get voice and tone guidelines | | get_copy_patterns | Get approved copy patterns | | get_cta_rules | Get CTA guidelines | | get_tokens | Get design tokens | | list_packs | List available style packs |

What Gets Validated?

The saas pack checks for:

Vocabulary

• Use simple words: "use" not "utilize", "help" not "assist"
• Avoid jargon: "synergy", "leverage", "paradigm shift"
• Avoid weak intensifiers: "very", "really", "extremely"

Patterns

• No "click here" (accessibility issue)
• No "we're sorry for any inconvenience" (corporate non-apology)
• No double "please" (sounds desperate)
• No starting with "Sorry" (lead with solutions)

CTAs

• Avoid generic: "Submit", "OK", "Yes/No", "Click here"
• Use specific actions: "Save", "Create", "Sign up", "Export"
• Max 4 words

Constraints

• Max 25 words per sentence
• No exclamation marks (in most contexts)
• First-person plural ("we", "our")
• Oxford comma

License

MIT