Substack MCP Server

A Model Context Protocol (MCP) server that enables Claude and other AI assistants to interact with Substack newsletters, posts, and user profiles.

Overview

This project converts the Substack API library into an Anthropic MCP server, allowing Claude to:

• Retrieve newsletter posts, podcasts, and recommendations
• Get user profile information and subscriptions
• Fetch post content and metadata
• Search for posts within newsletters
• Search across multiple Substack newsletters simultaneously
• Discover popular Substack newsletters by category

Installation

Prerequisites

• Python 3.10 or higher
• Claude for Desktop (for testing with Claude)

Installation Steps

# Clone the repository
git clone https://github.com/Greg-Swiftomatic/substack-mcp-server.git
cd substack-mcp-server

# Set up virtual environment
python -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate

# Install dependencies
pip install -r requirements.txt

Alternatively, you can use uv:

# Using uv for faster installation
curl -LsSf https://astral.sh/uv/install.sh | sh
uv venv
source .venv/bin/activate
uv pip install -r requirements.txt

Usage

Running the Server

python substack_mcp.py

Connecting to Claude for Desktop

1. Open your Claude for Desktop configuration file:

   • MacOS: ~/Library/Application Support/Claude/claude_desktop_config.json
   • Windows: %APPDATA%\Claude\claude_desktop_config.json

2. Add the server configuration:

{
    "mcpServers": {
        "substack": {
            "command": "python",
            "args": [
                "/ABSOLUTE/PATH/TO/substack-mcp-server/substack_mcp.py"
            ]
        }
    }
}

3. Restart Claude for Desktop

Using with Claude

Once configured, you can ask Claude questions like:

• "Show me recent posts from https://stratechery.com/"
• "What's the content of this post: https://stratechery.com/2023/the-ai-unbundling/"
• "Search for 'AI' on https://stratechery.com/"
• "Search for 'AI ethics' across multiple Substack newsletters"
• "What are popular technology newsletters on Substack?"
• "Who are the authors of https://stratechery.com/?"

See example queries for more examples.

Available Tools

This MCP server provides the following tools:

Tool	Description
get_newsletter_posts	Retrieves recent posts from a Substack newsletter
get_post_content	Gets the full content of a specific Substack post
search_newsletter	Searches for posts within a newsletter
search_across_substacks	Searches for content across multiple Substack newsletters
discover_popular_substacks	Discovers popular Substack newsletters by category
get_author_info	Retrieves information about a Substack author
get_newsletter_recommendations	Gets recommended newsletters for a publication
get_newsletter_authors	Lists authors of a Substack newsletter

Development

Project Structure

substack-mcp-server/
├── README.md
├── LICENSE
├── requirements.txt
├── Dockerfile
├── substack_mcp.py
└── examples/
    └── example_queries.md

Adding New Tools

To add new tools to the MCP server, add a new function to substack_mcp.py with the @mcp.tool() decorator:

@mcp.tool()
async def my_new_tool(param1: str, param2: int = 5) -> str:
    """
    Description of what the tool does.
    
    Args:
        param1: Description of param1
        param2: Description of param2 (default: 5)
    """
    # Tool implementation
    return "Result"

Cross-Substack Search

The search_across_substacks tool enables powerful research capabilities by searching multiple Substack newsletters simultaneously for specific topics. This allows for:

• Discovering diverse perspectives on a topic across different authors
• Comparing coverage of current events across publications
• Finding the most comprehensive content on niche topics

You can specify which newsletters to search or let the system use a curated list of popular newsletters. Results are organized by newsletter for easy comparison.

Substack Discovery

The discover_popular_substacks tool helps users find new newsletters based on categories of interest. Currently supported categories include:

• technology
• politics
• science
• culture
• economics

This feature makes it easier to discover high-quality content creators in specific domains.

Troubleshooting

If you encounter issues:

1. Check Claude's logs:

   # MacOS
   tail -n 20 -f ~/Library/Logs/Claude/mcp*.log
   
   # Windows
   type %APPDATA%\Claude\Logs\mcp*.log
   

2. Ensure your server runs without errors:

   python substack_mcp.py
   

3. Verify the configuration file paths in Claude for Desktop.

Contributing

Contributions are welcome! Please feel free to submit a pull request.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add some amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• NHagar/substack_api - The original Substack API library
• Model Context Protocol - Anthropic's MCP specification