About MCP Defender
MCP Defender is a desktop app that protects MCP traffic in AI apps such as Cursor, Claude, VS Code and Windsurf. It proxies tool call requests and responses and checks them against a set of signatures, aimed at developers who use third-party MCP tools.
Key features
- 01Automatic proxying of MCP tool call traffic
- 02Signature-based checks on intercepted data
- 03Alerts when harmful content is detected
- 04Asks the user to allow or block tool calls
- 05Supports Cursor, Claude, VS Code and Windsurf
Use cases
- 01Checking third-party MCP tool calls made from Cursor or Claude
- 02Blocking suspicious tool calls after user review
- 03Reducing MCP-related attack risk in VS Code or Windsurf
MCP support
MCP Defender sits between AI apps and MCP servers as a proxy, intercepting tool call traffic between the client and servers. It functions as a security layer for MCP clients.
Configuration
Local server config is the same for every client. Copy it into your client’s MCP config file.
We haven’t collected a package or remote endpoint for this server. Follow the instructions in the project README.
Tools
Local servers expose tools only once running on your machine, and the maintainer has not provided a tool list.
Details
From the project README
MCP Defender
Automatically protects MCP traffic in AI apps
MCP Defender has been acquired by Docker Inc.
🛡️ MCP Defender is a desktop app that protects AI apps like Cursor from a variety of attacks.
🚦 All MCP tool call requests and responses from AI apps are automatically proxied through MCP Defender.
🔎 The intercepted data is then checked against a set of signatures.
🔐 If anything harmful is detected, MCP Defender alerts you and asks if you want to allow or block the tool call.
Demos
https://github.com/user-attachments/assets/363ae2b1-e395-4cdc-b5ca-e9862baf89c3
Quick Start
Alternatively you can clone the git repo, and run it as follows:
# Install dependencies
npm install
# Start app
npm start
Which apps are automatically protected?
MCP Defender protects Cursor, Claude, Visual Studio Code and Windsurf.
License
MCP Defender is licensed under the AGPL-3.0 license. For more details, see the LICENSE.
Comments
New to MCP?
From what the protocol is to installing your first server, these answers cover most first questions.
An open protocol that defines how AI applications connect to external tools and data in a uniform way. Clients talk to the model; MCP servers provide tools, resources and prompt templates. They exchange standard messages, so one server can be reused by many clients.