Substack MCP Server

Substack MCP Server

A Model Context Protocol (MCP) Server for Substack enabling LLM clients to interact with Substack's API for automations like creating posts, managing drafts, and more.

Create and publish posts, work with subscribers and analytics, browse your reader feeds, manage tags and comments, and upload images — 27 tools exposed through one MCP server.

[!IMPORTANT]

Substack does not provide a public API for these operations. This server uses your authenticated

web session. Treat the session token exactly like a password: keep it local, never commit it, and

never include it or a complete Cookie header in a bug report.

Quick start

The fastest installation uses Node.js 22 or newer and npx.

1. Collect your Substack credentials

Sign in to Substack in your browser and open your publication dashboard. You need three values:

https://your-publication.substack.com.

• Publication URL — the full base URL of your publication, for example

Fetch/XHR, and reload the dashboard. Open a successful authenticated request to your publication. Under Request Headers, find the Cookie header and locate a session cookie named substack.sid or connect.sid. Copy its value without the cookie name or the rest of the header. If both names appear with different values, test them separately and locally with the read-only verification in step 3; never paste either value into an issue.

• Session token — open your browser's developer tools, select Network, filter to

its JSON response, copy the numeric id inside the user object.

• User ID — in the same Network panel, search for a successful publication_user request. In

If the browser UI differs, the illustrated credential guide shows the same requests. If authentication later stops working, sign in again and repeat these steps to obtain the current token.

2. Add the server to your MCP client

For clients that accept MCP JSON configuration, add:

{
  "mcpServers": {
    "substack": {
      "command": "npx",
      "args": ["-y", "substack-mcp@latest"],
      "env": {
        "SUBSTACK_PUBLICATION_URL": "https://your-publication.substack.com",
        "SUBSTACK_SESSION_TOKEN": "your-session-token",
        "SUBSTACK_USER_ID": "your-user-id"
      }
    }
  }
}

Replace the three example values, save the configuration, and restart your MCP client. Consult your client's documentation if it uses a different configuration format.

3. Verify the connection

Ask your client:

List my five most recent Substack drafts.

The client should call list_posts with status: "drafts". If it fails, check the client's MCP logs and the logging section below before opening an issue.

Docker quick start

To use the published Docker image instead of Node.js, add this server configuration:

{
  "mcpServers": {
    "substack": {
      "command": "docker",
      "args": [
        "run", "-i", "--rm",
        "-e", "SUBSTACK_PUBLICATION_URL",
        "-e", "SUBSTACK_SESSION_TOKEN",
        "-e", "SUBSTACK_USER_ID",
        "marcomoauro/substack-mcp:latest"
      ],
      "env": {
        "SUBSTACK_PUBLICATION_URL": "https://your-publication.substack.com",
        "SUBSTACK_SESSION_TOKEN": "your-session-token",
        "SUBSTACK_USER_ID": "your-user-id"
      }
    }
  }
}

🛠 Available Tools

createdraftpost - Create a draft post

Shortened. The full README is on GitHub.