# GenClass MCP server

> Enables coding agents to detect, replay, and prove fixes for race conditions in web applications by reordering network responses.

- Repository: https://github.com/genclass-dev/GenClass
- Page: https://hostedmcp.org/servers/genclass-dev/genclass
- Transport: stdio
- Stars: 11
- License: Apache-2.0
- Latest version: 0.2.2

## Install

### Claude Code

```sh
claude mcp add genclass -- npx -y @genclass/mcp
```

### Cursor (`~/.cursor/mcp.json`)

```json
{
  "mcpServers": {
    "genclass": {
      "command": "npx",
      "args": [
        "-y",
        "@genclass/mcp"
      ]
    }
  }
}
```

### VS Code (`.vscode/mcp.json`)

```json
{
  "servers": {
    "genclass": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "@genclass/mcp"
      ]
    }
  }
}
```

### VS Code CLI

```sh
code --add-mcp '{"name":"genclass","type":"stdio","command":"npx","args":["-y","@genclass/mcp"]}'
```

### Claude Desktop (`claude_desktop_config.json`)

```json
{
  "mcpServers": {
    "genclass": {
      "command": "npx",
      "args": [
        "-y",
        "@genclass/mcp"
      ]
    }
  }
}
```

### Codex (`~/.codex/config.toml`)

```toml
[mcp_servers.genclass]
command = "npx"
args = ["-y", "@genclass/mcp"]
```

### Gemini CLI (`~/.gemini/settings.json`)

```json
{
  "mcpServers": {
    "genclass": {
      "command": "npx",
      "args": [
        "-y",
        "@genclass/mcp"
      ]
    }
  }
}
```

## Tools (9)

- `genclass_status`
- `genclass_findings`
- `genclass_explain`
- `genclass_explore`
- `genclass_replay`
- `genclass_analytics`
- `genclass_setup`
- `genclass_scan`
- `genclass_clear`

## FAQ

### How does GenClass find race conditions?

It uses the genclass_explore tool to run application steps again with network responses delivered in different orders or with artificial delays.

### Can GenClass help prove that a bug is fixed?

Yes, it can replay the exact response order that caused the bug to verify it is reproduced before a fix and not reproduced after.

### Does GenClass generate automated tests?

Yes, the genclass_explain tool can write a Playwright test that fails when the bug is present.

### Is my data private when using GenClass?

By default, everything stays on your local machine.