# subelsky/bundler_mcp [Health: Active]

**Category:** 🧮 Data Science Tools  
**Repository:** https://github.com/subelsky/bundler_mcp  
**GitHub Stars:** 20  
**npm Downloads (last month):** 1082816  
**Views:** 2  
**Installs:** 0  
**Upvotes:** 0  
**Directory Page:** https://allmcps.com/mcp/subelsky-bundler-mcp

## Description
Enables agents to query local information about dependencies in a Ruby project's Gemfile.

## Tools
Capabilities this server exposes over MCP:

- **README**
- **CHANGELOG**

## Claude Desktop Quick Installation
Install path detected from listing signals. Uses `npx` (confidence: high):

```json
"mcpServers": {
  "bundler-mcp": {
    "command": "npx",
    "args": ["-y","@modelcontextprotocol/inspector"],
    "env": {
      "BUNDLE_GEMFILE": "",
      "BUNDLER_MCP_LOG_FILE": ""
    }
  }
}
```

**Requires environment variables:** `BUNDLE_GEMFILE`, `BUNDLER_MCP_LOG_FILE` — the values above are empty placeholders; fill in real credentials before running (see the repository for what each one is for).

## Documentation & README

# 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).

[![CI](https://github.com/subelsky/bundler_mcp/actions/workflows/main.yml/badge.svg)](https://github.com/subelsky/bundler_mcp/actions/workflows/main.yml)
[![Gem Version](https://badge.fury.io/rb/bundler_mcp.svg)](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`)

![list_project_gems tool](https://raw.githubusercontent.com/subelsky/bundler_mcp/HEAD/docs/list_project_gems.png)

#### get_gem_details

Retrieves detailed information about a specific gem, including:

- Version
- Description
- Installation path
- Top-level documentation locations
- Source code file locations

![get_gem_details tool](https://raw.githubusercontent.com/subelsky/bundler_mcp/HEAD/docs/get_gem_details.png)

## 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)