Callrail MCP vs Opn MCP

In-depth architectural comparison of the Callrail MCP and Opn MCP MCP servers. Compare execution transports, security boundaries, tool capabilities, quality scores, and ready-to-paste client installation snippets for Claude, Cursor, Windsurf, and VS Code.

Which MCP Server Should You Choose?

Choose Callrail MCP when:

• You need dedicated capabilities in the Marketing domain.
• You prefer local stdio subprocess transport architecture.
• Your security boundary fits: API Key required (BYOK (Pay Provider Direct)).
• You have access to required keys: CALLRAIL_API_KEY, CALLRAIL_API_KEY_FILE.
• Primary tools included: list_accounts, list_companies, list_trackers.

Explore Callrail MCP Details

Choose Opn MCP when:

• You need dedicated capabilities in the Marketing domain.
• You prefer local stdio subprocess transport architecture.
• Your security boundary fits: API Key required (Free / Open Source).
• You have access to required keys: OPN_API_KEY, OPN_BASE_URL.
• Primary tools included: shorten_url, shorten_urls_bulk, list_links.

Feature & Specification Comparison

Specification	Callrail MCP pghdma Marketing	Opn MCP ysalitrynskyi Marketing
Summary	CallRail REST API v3 integration with 49 tools for call tracking, form submissions, transcripts, full CRUD on tags/trackers/companies/users, plus agency-specific aggregation tools (usagesummary for per-client cost attribution, compareperiods for MoM deltas, bulkupdatecalls with dry-run, spamdetector, calleligibilitycheck for Google Ads conversion debugging). Built by an actual CallRail customer for agency use. Install: pipx install callrail-mcp.	Shorten links, read click analytics, generate branded QR codes, and manage links on opn.onl — the open-source, self-hostable URL shortener. Works with the hosted service or your own instance.
Category & Scope

Tools & Capabilities Breakdown

Ready-to-Paste Client Configurations

Paste either (or both) of these JSON server blocks into your client config file (e.g. claude_desktop_config.json or ~/.cursor/mcp.json).

{
  "mcpServers": {
    "pghdma-callrail-mcp": {
      "command": "uvx",
      "args": [
        "callrail-mcp"
      ],
      "env": {
        "CALLRAIL_API_KEY": "YOUR_CALLRAIL_API_KEY_HERE",
        "CALLRAIL_API_KEY_FILE": "YOUR_CALLRAIL_API_KEY_FILE_HERE"
      }
    }
  }
}

{
  "mcpServers": {
    "ysalitrynskyi-opn-mcp": {
      "command": "npx",
      "args": [
        "-y",
        "opn-mcp"
      ],
      "env": {
        "OPN_API_KEY": "YOUR_OPN_API_KEY_HERE",
        "OPN_BASE_URL": "YOUR_OPN_BASE_URL_HERE"
      }
    }
  }
}

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