# add_to_domain_blacklist (/docs/mcp/tools/add-to-domain-blacklist)

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**Block domains** · Changes data

Blocks company domains from becoming new leads on a website (e.g. your own company, competitors, existing customers). Domains are saved as one new named group; a group name that already exists on the website is refused (405), so pick a new name, or remove the group and add it again with the full list. Full URLs are reduced to their hostname. websiteId comes from list_websites; existing groups from get_domain_blacklist.

| Connection | Account URL, team member URL or OAuth |
| --- | --- |

## Parameters [#parameters]

| Parameter | Type | Required | Description |
| --- | --- | --- | --- |
| `websiteId` | `string` | Yes | Website ID from list_websites. |
| `csv` | `string` | Yes | Name of the new group, e.g. "internal" or "customers". Must not already exist on this website. |
| `domains` | `string[]` | Yes | Domains to block, e.g. ["acme.example", "competitor.example"]. URLs are accepted and reduced to the hostname (a www. prefix is kept). |

## Tool definition [#tool-definition]

What your assistant receives from `tools/list`:

```json
{
  "name": "add_to_domain_blacklist",
  "title": "Block domains",
  "annotations": {
    "title": "Block domains",
    "readOnlyHint": false,
    "destructiveHint": false,
    "idempotentHint": false,
    "openWorldHint": false
  },
  "inputSchema": {
    "type": "object",
    "properties": {
      "websiteId": {
        "type": "string",
        "description": "Website ID from list_websites."
      },
      "csv": {
        "type": "string",
        "description": "Name of the new group, e.g. \"internal\" or \"customers\". Must not already exist on this website."
      },
      "domains": {
        "type": "array",
        "items": {
          "type": "string"
        },
        "description": "Domains to block, e.g. [\"acme.example\", \"competitor.example\"]. URLs are accepted and reduced to the hostname (a www. prefix is kept)."
      }
    },
    "required": [
      "websiteId",
      "csv",
      "domains"
    ]
  }
}
```