# crosscheck MCP server

> Provides an independent second opinion on AI-generated drafts to catch errors, contradictions, leaked secrets, and prompt injections.

- Repository: https://github.com/maxugc/crosscheck
- Page: https://hostedmcp.org/servers/maxugc/crosscheck
- Transport: stdio, remote
- Stars: 1
- License: MIT
- Latest version: 0.6.0

## Install

### Claude Code

```sh
claude mcp add --env 'CROSSCHECK_WALLET_KEY=<YOUR_CROSSCHECK_WALLET_KEY>' crosscheck -- npx -y crosscheckapi
```

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

```json
{
  "mcpServers": {
    "crosscheck": {
      "command": "npx",
      "args": [
        "-y",
        "crosscheckapi"
      ],
      "env": {
        "CROSSCHECK_WALLET_KEY": "<YOUR_CROSSCHECK_WALLET_KEY>"
      }
    }
  }
}
```

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

```json
{
  "servers": {
    "crosscheck": {
      "type": "stdio",
      "command": "npx",
      "args": [
        "-y",
        "crosscheckapi"
      ],
      "env": {
        "CROSSCHECK_WALLET_KEY": "<YOUR_CROSSCHECK_WALLET_KEY>"
      }
    }
  }
}
```

### VS Code CLI

```sh
code --add-mcp '{"name":"crosscheck","type":"stdio","command":"npx","args":["-y","crosscheckapi"],"env":{"CROSSCHECK_WALLET_KEY":"<YOUR_CROSSCHECK_WALLET_KEY>"}}'
```

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

```json
{
  "mcpServers": {
    "crosscheck": {
      "command": "npx",
      "args": [
        "-y",
        "crosscheckapi"
      ],
      "env": {
        "CROSSCHECK_WALLET_KEY": "<YOUR_CROSSCHECK_WALLET_KEY>"
      }
    }
  }
}
```

### Codex

```sh
codex mcp add crosscheck --env 'CROSSCHECK_WALLET_KEY=<YOUR_CROSSCHECK_WALLET_KEY>' -- npx -y crosscheckapi
```

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

```toml
[mcp_servers.crosscheck]
command = "npx"
args = ["-y", "crosscheckapi"]

[mcp_servers.crosscheck.env]
CROSSCHECK_WALLET_KEY = "<YOUR_CROSSCHECK_WALLET_KEY>"
```

### Gemini CLI

```sh
gemini mcp add -s user -e 'CROSSCHECK_WALLET_KEY=<YOUR_CROSSCHECK_WALLET_KEY>' crosscheck npx -- -y crosscheckapi
```

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

```json
{
  "mcpServers": {
    "crosscheck": {
      "command": "npx",
      "args": [
        "-y",
        "crosscheckapi"
      ],
      "env": {
        "CROSSCHECK_WALLET_KEY": "<YOUR_CROSSCHECK_WALLET_KEY>"
      }
    }
  }
}
```

## Environment variables

| Name | Required | Secret | Description |
|---|---|---|---|
| `CROSSCHECK_WALLET_KEY` | no | yes | Private key of a dedicated EVM wallet with a few dollars of USDC on Base (or test USDC on Base Sepolia). Pays for checks. |
| `CROSSCHECK_MAX_USD` | no | no | Refuse to pay more than this per check. Default 0.10. |
| `CROSSCHECK_NETWORKS` | no | no | Networks to pay on, in order of preference. Default eip155:8453,eip155:84532. Set eip155:84532 for test USDC only. |

## FAQ

### How much does a check cost?

Each check costs $0.02 in USDC on Base for up to 12,000 units, which is one per English character.

### Can I test the service without using real money?

Yes, you can use test USDC on Base Sepolia by setting the CROSSCHECK_NETWORKS environment variable to eip155:84532.

### Does the service require an account or API key?

No, there is no account or API key required to use the service.

### Is my data kept private?

The draft is sent to the review model and then deleted once the check is finished; only the hash is retained.