MCP Server Plugin for KOReader

A KOReader plugin that implements a Model Context Protocol (MCP) server, enabling AI assistants to interact with your e-books in real-time.

What is MCP?

The Model Context Protocol (MCP) is an open standard that enables AI assistants to securely connect to external data sources and tools. This plugin implements an MCP server that exposes your KOReader book content and functionality to compatible AI assistants.

Features

• Book Content Access: AI assistants can read your current book's content at different scopes (current page, chapter, specific page ranges)
• Metadata Retrieval: Access book metadata including title, author, reading progress, and statistics
• Interactive Tools: Search within books, navigate to pages, get table of contents, add highlights and notes
• Resource Subscriptions: Subscribe to resources and receive automatic notifications when they change (page turns, book changes)
• Client Features (MCP 2025-03-26):
  • Sampling: Server can request LLM completions from the client
  • Elicitation: Server can request user input (confirmations, text input, choices)
  • Logging: Server can send log messages to the client
• Secure Local Network: Server binds to your local network only
• Cloud Relay: Access your e-reader from anywhere via a cloud relay

Why not just use the KOAssistant plugin?

It's a great plugin and I recommend trying it out! I personally use both.

• KOAssistant uses an API and requires setting up access keys (not a problem, but a bit more technical setup)
• It's very convenient for quick interaction on-device: e.g. translating or explaining selected text
• It's not great for longer interactions that require typing which is usually a pain on e-readers
• While KOAssistant chats can be saved, they will not appear in your main AI assistant app's chat history (which may be desired because of the memories that your AI assistant builds over time)

Where does KOReader MCP shine?

• You are reading a book and want to have a full conversation about it with your AI assistant (e.g., Claude, ChatGPT, DeepSeek or even local LLMs)
• It can be especially useful when studying or reading on complex topics (research, philosophy, technical books), where you want to discuss ideas and brainstorm
• You can open a chat on your phone or computer, and talk to the AI about your current reading context without finicky interactions on the slow e-reader screen
• The chat history and memories are stored in your AI assistant app, keeping everything in one place and allowing for richer interactions over time (e.g. making connections between conversations or even different books)
  • Note: this is optional and is totally up to you how you want to use it

Installation

Important

This is an early implementation. Use it at your own risk. I make NO GUARANTEES about stability, security, or data integrity. You're welcome to review the code and suggest improvements.

Via an app store plugin (recommended)

Use the App Store plugin (or any other similar one) to install the MCP server plugin directly from KOReader. Simply search for "MCP" and install the plugin via the UI. This method ensures you get updates automatically.

Manually

1. Download or clone this repository
2. Copy the mcp.koplugin directory to your KOReader plugins folder
3. Restart KOReader

To update, repeat the steps above with the latest version.

Usage

Starting the Server

1. Tap the menu (top of screen) and open 🛠️ Tools
2. You will see a checkbox for MCP server
   • Tap it to start or stop the server
   • Long-press to switch between local/remote modes or to see the details

Settings

1. Tap the menu and navigate to ⚙️ Settings → Network → MCP server
2. Configure server settings:

   • Start server automatically: Enable to start the server when KOReader launches (requires WiFi)

   • Idle timeout: Set inactivity period before auto-stopping the server.
     _{When the idle timeout is enabled, you'll see a warning notification 5 seconds before the server stops. Tap the notification to reset the idle timer and keep the server alive.}

   • Turn off WiFi on idle timeout: Save battery by disabling WiFi when server stops due to idle timeout

3. Switch between local and cloud relay modes:
   • Local mode: Server listens on local network only
   • Cloud relay: Enable to use the cloud relay for remote access

Tip

Hold any menu item to open the help tooltip

Connecting an AI Assistant

Check the MCP server status in the Tools menu for the MCP server address. Use this address to configure your AI assistant or MCP client (e.g., Claude Desktop, Claude Mobile).

Claude

1. Go to Settings → Connectors → Add custom connector, or just us this link: https://claude.ai/settings/connectors?modal=add-custom-connector.
2. Enter the name (e.g., "KOReader") and the MCP server URL.
3. Open a new chat and in the ➕ menu you should see the new connector available. You can either add resources to the context, or ask it to use tools to fetch data from your book.

Chatting About Your Book

Once connected, you can ask your AI assistant questions like:

• "What is this book about?"
• "Summarize the current chapter"
• "What does the quote on this page mean?"
• "Search for other mentions of [character/topic] on this page and explain their significance"
• "Add a note with a translation of this selected text"
• "Highlight this important passage"

Assistant will use the MCP resources and tools to understand which book you're reading, what's on your screen, search within the book, and provide relevant responses. You can also ask the assistant to add highlights and notes to your book based on your conversation.

Tip

It might be helpful to create a separate project with more focused instructions for using KOReader MCP or even for a particular book that you want to discuss with your AI assistant. This will keep the context relevant and maintain separate memory for different books or topics.

MCP server capabilities

Warning

This is an early implementation and this list may change and be not up-to-date.

Resources

The plugin exposes these resources:

Current Book Resources

Resource URI	Description
book://current/context	Current reading context (page, chapter, selection)
book://current/metadata	Book metadata (title, author, progress, etc.)
book://current/toc	Table of contents
book://current/bookmarks	Bookmarks and highlights in the current book
book://current/pages/{range}	Text from specific pages (e.g., 5 or 10-15)
book://current/chapters/{idx}	Text from a specific chapter by index

Library Resources

Resource URI	Description
library://books	List of all books in the library
library://collections	Book collections/shelves
library://history	Reading history
library://books/{path}	Metadata for a specific book by path

Tools

The plugin provides these callable tools:

Tool	Description	Parameters
get_reading_context	Get current reading context (book, chapter, page, selection/highlight focus)	extra_pages_before (optional), extra_pages_after (optional)
get_book_metadata	Get full book metadata (for clients without resource support)	None
read_pages	Read text from specific pages or chapters	pages (e.g., "5" or "10-15"), chapter (index)
search_book	Search for text in the book	query, case_sensitive (optional)
goto_page	Navigate to a specific page	page
annotate	Add highlight or note to text	note (optional), text (optional), start (optional), end (optional)

Tool Annotations

All tools include MCP annotations to help AI assistants understand their behavior:

• readOnlyHint: Tools like get_reading_context, get_book_metadata, read_pages, search_book are read-only
• destructiveHint: The annotate tool modifies the document (false for destructive, but still modifying)
• idempotentHint: Multiple calls with the same parameters produce the same result
• openWorldHint: Whether the tool interacts with external entities

Prompts

Prompts are pre-defined conversation starters for common reading companion interactions. MCP clients that support prompts (like Claude) can present these as quick actions.

Prompt	Title	Description
explain	Explain This	Explain selected text or current page content
summarize	Summarize	Summarize page, chapter, or reading progress
discuss	Let's Discuss	Start a conversation about themes and ideas
research	Research This	Get background info about book, author, or historical context
note	Take a Note	Create and save annotations with assistant help
quiz	Quiz Me	Test comprehension with generated questions
translate	Translate	Translate text to another language
recommend	Recommend Books	Get personalized book recommendations

Server-Initiated Features (MCP 2025-03-26)

The plugin supports advanced MCP features that enable the server to communicate back to the client:

Resource Notifications

When clients subscribe to resources (e.g., book://current/page), the server automatically sends notifications when:

• The current page changes
• The book changes (open/close)
• Selected text changes

This enables real-time awareness of what the user is reading.

Logging

The server can send log messages to the client at various levels: debug, info, notice, warning, error, critical, alert, emergency

Clients can set the minimum log level via logging/setLevel.

Sampling & Elicitation (Prepared for Future Use)

The infrastructure is in place for server-initiated requests:

• Sampling: Request LLM completions from the client
• Elicitation: Request user confirmations, text input, or choices from forms

These features require client support and are ready for when MCP clients implement them.

Local & Remote Modes

Local Mode

In local mode, the MCP server runs on your e-reader and listens for connections on your local network (WiFi). This would be the default mode, but unfortunately some AI clients (most notably Claude Mobile) cannot connect to local network addresses and require a fully remote-accessible server.

Current limitations: Server-initiated features (resource notifications, logging) are not yet available in local mode because HTTP is request/response only. These features work fully in remote mode via the cloud relay. See PR #8 for work-in-progress on adding bidirectional communication via long-polling.

So for now this mode is kept for testing and limited use with compatible clients. I've tested it with GitHub Copilot with this configuration (replace LOCAL_IP):

"koreader": {
  "type": "http",
  "url": "http://LOCAL_IP:8788"
}

[!INFO] If you test it with other clients in local mode, please share your experience. Or if you have ideas on how to make local mode more useful, let me know!

Remote Mode (Cloud Relay)

The cloud relay feature allows you to access your MCP server from anywhere — Claude Desktop, Claude Mobile, or other AI tools — without complex network setup like VPNs or port forwarding.

graph LR
  A["E-Reader<br/>(KOReader)"] --> B["Cloud Relay<br/>(Cloudflare)"]
  B --> C["Claude/Client"]
  C --> B
  B --> A

Loading

1. On first connection, your e-reader generates a device ID (based on your device type) and a random 6-digit passcode
2. The passcode is hashed (SHA-256) and sent to the relay — the plaintext passcode never leaves your device
3. The relay assigns a unique URL for your device
4. Your e-reader displays the passcode to you (save it!)
5. You configure your AI assistant with the URL and authenticate via the OAuth login screen using the passcode
6. AI clients exchange the authorization code for a short-lived access token

Authentication Flow

When you first start the MCP server in remote mode, you'll see:

• The relay URL
• Your device ID
• Your unique 6-digit passcode
• Instructions for connecting your AI assistant

The relay uses OAuth 2.1 Authorization Code flow with PKCE, so MCP clients that support OAuth will handle authentication automatically.

Tip

You can view your credentials in the MCP settings menu (Settings → Network → MCP server)

Important

The relay is just a bridge forwarding requests between your e-reader and AI clients. It does not store any book content or personal data. The relay never receives your actual passcode — only its hash.

The relay implementation is open source: mcp-relay-cloudflare. You can deploy your own instance for full control. By default, plugin uses the relay I deployed for myself. I'll be sharing it as long as it's within the free tier limits.

Security

• Zero-knowledge passcode: Passcode is generated locally and only the SHA-256 hash is sent to the relay
• OAuth 2.1 Authorization Code + PKCE: MCP clients authenticate via the /authorize login screen using your device ID + passcode, then exchange a code for a token
• Short-lived tokens: Access tokens expire in 1 hour
• Audience validation: Tokens are bound to your specific device
• All traffic is encrypted (HTTPS)
• The relay doesn't store any book content, only forwards authenticated requests
• You can reset your device ID and passcode anytime from the settings menu

Warning

Current implementation does not implement SSL certificate verification for the relay server

References

• Built for KOReader
• Implements Model Context Protocol by Anthropic
• Inspired by koassistant.koplugin