substack-mcp

Read and publish to any Substack publication — single Rust binary, no Node.js runtime.

Prerequisites

• A Substack account

• Your connect.sid session cookie — get it in 3 steps:

  1. Log in at substack.com
  2. Open DevTools → Application → Cookies → https://substack.com
  3. Copy the value of the connect.sid cookie

  Works with the raw value (s:abc…) or the URL-encoded form (s%3Aabc…) — the server decodes automatically.

• Your publication URL (e.g. https://yourname.substack.com) — only required for draft and publish tools

Credentials are read from environment variables only and are never written to disk.

Installation

npm install -g @kembec/substack-mcp

Or run directly without installing:

npx @kembec/substack-mcp

Configuration

Two environment variables:

| Variable | Required for | Example | |----------|-------------|---------| | SUBSTACK_SID | Authenticated tools | s:0w29uWWh… | | SUBSTACK_PUBLICATION_URL | Draft and publish tools | https://yourname.substack.com |

Cursor

Add to ~/.cursor/mcp.json:

{
  "mcpServers": {
    "substack": {
      "command": "npx",
      "args": ["-y", "@kembec/substack-mcp"],
      "env": {
        "SUBSTACK_SID": "s:your-connect-sid-value",
        "SUBSTACK_PUBLICATION_URL": "https://yourname.substack.com"
      }
    }
  }
}

Claude Desktop

Add to claude_desktop_config.json:

{
  "mcpServers": {
    "substack": {
      "command": "npx",
      "args": ["-y", "@kembec/substack-mcp"],
      "env": {
        "SUBSTACK_SID": "s:your-connect-sid-value",
        "SUBSTACK_PUBLICATION_URL": "https://yourname.substack.com"
      }
    }
  }
}

Codex CLI

Add to ~/.codex/config.toml:

[mcp_servers.substack]
command = "npx"
args = ["-y", "@kembec/substack-mcp"]
enabled = true

[mcp_servers.substack.env]
SUBSTACK_SID = "s:your-connect-sid-value"
SUBSTACK_PUBLICATION_URL = "https://yourname.substack.com"

Tools

Public — no credentials needed

| Tool | Parameters | Description | |------|-----------|-------------| | get_profile | slug: string | Fetch a writer's public profile | | get_posts | publication_url: string, limit?: number, offset?: number | List published posts | | get_post | publication_url: string, post_slug: string | Get a single post with content | | get_comments | post_id: number, limit?: number | List comments on a post | | get_notes | user_id: number, limit?: number, offset?: number | List a user's notes |

Authenticated — requires SUBSTACK_SID

| Tool | Parameters | Description | |------|-----------|-------------| | create_note | body: string | Post a note to your profile | | like_post | post_id: number | Like a post |

Publication — requires SUBSTACK_SID + SUBSTACK_PUBLICATION_URL

| Tool | Parameters | Description | |------|-----------|-------------| | list_drafts | limit?: number, offset?: number | List unpublished drafts | | create_draft | title: string, body: string, audience?: "everyone"\|"paid" | Create a new draft | | update_draft | draft_id: number, title?: string, body?: string | Edit an existing draft | | publish_post | draft_id: number, send_email?: boolean | Publish a draft |

Warning — publish_post is irreversible. When send_email is true (default), the post is published and emails are sent to all subscribers immediately. Always verify the draft content with list_drafts or get_post before publishing.

Building from source

Requires Rust 1.78+:

git clone https://github.com/Kembec/substack-mcp.git
cd substack-mcp
cargo build --release
./target/release/substack-mcp

License

MIT