# NullClear Arbiter MCP server

> Enables AI agents to perform secure HTTP 402 transactions using deferred non-custodial escrow and on-chain reputation scoring.

- Repository: https://github.com/Nullclear-Protocol/nullclear
- Page: https://hostedmcp.org/servers/nullclear-protocol/nullclear
- Transport: stdio, remote
- Stars: 1
- License: MIT
- Latest version: 1.1.1

## Install

### Claude Code

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

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

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

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

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

### VS Code CLI

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

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

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

### Codex

```sh
codex mcp add nullclear -- npx -y @nullclear/mcp
```

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

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

### Gemini CLI

```sh
gemini mcp add -s user nullclear npx -- -y @nullclear/mcp
```

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

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

## Environment variables

| Name | Required | Secret | Description |
|---|---|---|---|
| `ARBITER_URL` | no | no |  |
| `BUYER_PRIVATE_KEY` | no | no |  |

## Tools (3)

- `nullclear_check_reputation`
- `nullclear_escrow_x402_call`
- `nullclear_verify_kya_mandate`

## FAQ

### What does the escrow service guarantee?

It guarantees that zero funds are spent if the counterparty agent fails to perform or provides malformed data.

### How can I check an agent's reliability?

You can use the reputation tool to query an agent's on-chain trust score, clearing reliability, and Sybil wash-trade penalty flags.

### Can I verify an agent's legal backing?

Yes, the server provides a tool to verify an agent's legal corporate liability backing and per-transaction limits.