whatsapp-mcp: WhatsApp conversation search MCP server released without sending functionality

• Released a read-only WhatsApp MCP server without a message sending feature to reduce the risk of data leakage.
• Uses the Cloudflare Workers Paid plan ($5 per month) to store conversation history in SQLite within a Durable Object.
• Connects as a Linked Device using the Baileys library and automatically syncs at 04:00 UTC daily.
• Risks of prompt injection and terms of service violations due to the use of unofficial protocols exist.

Architecture and Operation

• Composed of one Worker and one Durable Object, storing new messages via a Pull method rather than maintaining a persistent connection.
• Applied a ws package Shim and WebAssembly module extraction to run Node.js-based Baileys in workerd.
• Upon agent requests, data is queried from the Durable Object's SQLite via the MCP client.

Security and Limitations

• Unlike lharries/whatsapp-mcp, the absence of sending tools blocks the path for conversation history leakage through WhatsApp.
• Photos and voice messages are stored only as text labels, and downloading the originals is not possible.
• Vulnerable to prompt injection attacks via messages from strangers, so caution is required when used alongside external communication tools.