# Rails Diff Mcp

> MCP server for Rails version diffs

- **Type:** MCP server
- **Install:** `agentstack add mcp-alexzeitler-rails-diff-mcp`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [AlexZeitler](https://agentstack.voostack.com/s/alexzeitler)
- **Installs:** 0
- **Category:** [Integrations](https://agentstack.voostack.com/c/integrations)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [AlexZeitler](https://github.com/AlexZeitler)
- **Source:** https://github.com/AlexZeitler/rails-diff-mcp

## Install

```sh
agentstack add mcp-alexzeitler-rails-diff-mcp
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Rails Diff MCP Server

MCP server that exposes Rails version diffs as tools. Data comes from the [railsdiff/rails-new-output](https://github.com/railsdiff/rails-new-output) GitHub repository, where each Rails version is tagged with the output of `rails new`.

## Tools

| Tool | Description |
|------|-------------|
| `list_rails_versions` | List all available Rails versions (sorted) |
| `compare_rails_versions` | Compare two versions — returns a list of changed files |
| `get_file_diff` | Get the patch for a specific file between two versions |

## Setup

### Prerequisites

- Docker and Docker Compose
- Optional: `GITHUB_TOKEN` env var to avoid GitHub API rate limits

### Start the server

```sh
docker compose up -d
```

The server listens on `http://localhost:8080/mcp` with a health check at `http://localhost:8080/healthz`.

### Register in your MCP client

Example for Claude Code:

```sh
claude mcp add --transport http rails-diff http://localhost:8080/mcp
```

Restart your MCP client to pick up the new server.

## Development

```sh
bun install
bun src/index.ts
```

The server starts on port 8080 by default. Override with `PORT` env var.

## Configuration

| Env var | Description | Default |
|---------|-------------|---------|
| `PORT` | Server listen port | `8080` |
| `GITHUB_TOKEN` | GitHub personal access token (raises API rate limit) | none |

## Credits

Built on top of [RailsDiff](https://github.com/railsdiff/railsdiff) by [Andy Stewart](https://github.com/airblade) and contributors. The diff data comes from [railsdiff/rails-new-output](https://github.com/railsdiff/rails-new-output).

## Source & license

This open-source MCP server is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [AlexZeitler](https://github.com/AlexZeitler)
- **Source:** [AlexZeitler/rails-diff-mcp](https://github.com/AlexZeitler/rails-diff-mcp)
- **License:** MIT

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/mcp-alexzeitler-rails-diff-mcp
- Seller: https://agentstack.voostack.com/s/alexzeitler
- Browse the marketplace: https://agentstack.voostack.com/browse

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Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.