Joern MCP Server
A simple MCP Server for Joern.
Project Introduction
This project is an MCP Server based on Joern, providing a series of features to help developers with code review and security analysis.
Environment Requirements
- Python >= 3.10 (default 3.12) & uv
- Joern
Installation Steps
- Clone the project locally:
git clone https://github.com/sfncat/mcp-joern.git
cd mcp-joern
- Install Python dependencies:
uv venv .venv
source .venv/bin/activate
uv sync
Project Structure
├── server.py # MCP Server main program
├── test_mcp_client.py # Test program for joern server and mcp tool
├── test_sc_tools.py # Direct test program for sc tools
├── common_tools.py # Common utility functions
├── server_tools.py # Server utility functions
├── server_tools.sc # Scala implementation of server utility functions
├── server_tools_source.sc # Scala implementation of server utility functions,use sourceCode to get the source code of method
├── requirements.txt # Python dependency file
├── sample_cline_mcp_settings.json # Sample cline mcp configuration file
└── env_example.txt # Environment variables example file
Usage
- Start the Joern server:
joern -J-Xmx40G --server --server-host 127.0.0.1 --server-port 16162 --server-auth-username user --server-auth-password password --import server_tools.sc
Or
joern -J-Xmx40G --server --server-host 127.0.0.1 --server-port 16162 --server-auth-username user --server-auth-password password --import server_tools_source.sc
set _JAVA_OPTIONS=-Dfile.encoding=UTF-8
- Copy env_example.txt to .env
Modify the configuration information to match the joern server startup configuration
- Run the test connection:
Modify the information in
test_mcp_client.py to confirm the joern server is working properlyuv run test_mcp_client.py
Starting MCP server test...
==================================================
Testing server connection...
[04/16/25 20:38:54] INFO Processing request of type CallToolRequest server.py:534
Connection test result: Successfully connected to Joern MCP, joern server version is XXX
- Configure MCP server
Configure the mcp server in cline, refer to
sample_cline_mcp_settings.json. - Use MCP server
Ask questions to the large language model, refer to
prompts_en.md
Development Notes
.env file is used to store environment variables.gitignore file defines files to be ignored by Git version controlpyproject.toml defines the Python configuration for the project- MCP tool development
- Implement in
server_tools.sc, add definitions in server_tools.py, and add tests in test_mcp_client.py
Contribution Guidelines
Welcome to submit Issues and Pull Requests to help improve the project.
Welcome to add more tools.
References
https://github.com/flankerhqd/jebmcp
https://docs.joern.io/server/
https://docs.joern.io/interpreter/