README.md•3.48 kB
# BundlerMCP
A Model Context Protocol (MCP) server enabling AI agents to query information about dependencies in a Ruby project's `Gemfile`. Built with [fast-mcp](https://github.com/yjacquin/fast-mcp).
[](https://github.com/subelsky/bundler_mcp/actions/workflows/main.yml)
[](https://badge.fury.io/rb/bundler_mcp)
## Installation
Install the gem and add to the application's Gemfile by executing:
```bash
bundle add bundler_mcp --group=development
```
## Usage
1. Generate the binstub:
```bash
bundle binstubs bundler_mcp
```
2. Configure your client to execute the binstub. Here are examples that work for Claude and Cursor:
### Basic Example (mcp.json)
```json
{
"mcpServers": {
"bundler-mcp": {
"command": "/Users/mike/my_project/bin/bundler_mcp"
}
}
}
```
### Example with logging and explicit Gemfile
```json
{
"mcpServers": {
"bundler-mcp": {
"command": "/Users/mike/my_project/bin/bundler_mcp",
"env": {
"BUNDLER_MCP_LOG_FILE": "/Users/mike/my_project/log/mcp.log",
"BUNDLE_GEMFILE": "/Users/mike/my_project/subdir/Gemfile"
}
}
}
}
```
### Documentation
[Available on RubyDoc](https://www.rubydoc.info/gems/bundler_mcp/)
### Available Tools
The server provides two tools for AI agents:
#### list_project_gems
Lists all bundled Ruby gems with their:
- Versions
- Descriptions
- Installation paths
- Top-level documentation locations (e.g. `README` and `CHANGELOG`)
#### get_gem_details
Retrieves detailed information about a specific gem, including:
- Version
- Description
- Installation path
- Top-level documentation locations
- Source code file locations
## Environment Variables
- `BUNDLE_GEMFILE`: Used by Bundler to locate your Gemfile. If you use the binstub method described in the [Usage](#usage) section, this is usually not needed.
- `BUNDLER_MCP_LOG_FILE`: Path to log file. Useful for troubleshooting (defaults to no logging)
## Development
After checking out the repo, run `bin/setup` to install dependencies and `bundle exec rspec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.
### Testing with the MCP Inspector
You can test the server directly using the [MCP inspector](https://modelcontextprotocol.io/docs/tools/inspector):
```bash
# Basic usage
npx @modelcontextprotocol/inspector ./bin/bundler_mcp
# With logging enabled
BUNDLER_MCP_LOG_FILE=/tmp/log/mcp.log npx @modelcontextprotocol/inspector ./bin/bundler_mcp
# With custom Gemfile
BUNDLE_GEMFILE=./other/Gemfile npx @modelcontextprotocol/inspector ./bin/bundler_mcp
```
### Release Process
To install this gem onto your local machine, run `bundle exec rake install`. To release a new version:
1. Update the version number in `version.rb`
2. Run `bundle exec rake release`
This will:
- Create a git tag for the version
- Push git commits and the created tag
- Push the `.gem` file to [rubygems.org](https://rubygems.org)
## Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/subelsky/bundler_mcp.
## License
Open source under the terms of the [MIT License](https://opensource.org/licenses/MIT).
## Author
[Mike Subelsky](https://subelsky.com)