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RunStack Checks

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External checks of TLS, HTTP headers, email domain, DNS and ports, with cause and fix

Source code Website Documentation

Install

Add this to your client's MCP configuration (Claude Desktop: claude_desktop_config.json; Cursor: .cursor/mcp.json; VS Code and others use the same "mcpServers" shape).

Remote (streamable-http)
Claude Code 
claude mcp add --transport http runstack-checks 'https://runstack.pro/api/mcp' --header 'X-RunStack-Key: <Free API key from https://runstack.pro/account (rsk_...)>'
JSON configuration (Claude Desktop, Cursor, VS Code) 
{
    "mcpServers": {
        "runstack-checks": {
            "type": "http",
            "url": "https://runstack.pro/api/mcp",
            "headers": {
                "X-RunStack-Key": "<Free API key from https://runstack.pro/account (rsk_...)>"
            }
        }
    }
}

Documentation

From the project's README on GitHub, refreshed weekly. Links open on GitHub.

Contents
  1. RunStack MCP — external infrastructure checks for AI agents
  2. Tools
  3. Example (abridged, real output)
  4. Setup
  5. Language
  6. Links

RunStack MCP — external infrastructure checks for AI agents

Remote MCP server that checks your public infrastructure from the outside — the way users, browsers and other mail servers see it — and returns a diagnosis: verdict, findings with cause and fix, and a shareable report link.

Nothing runs locally and nothing runs on your servers: only public data is checked.

  • Endpoint: https://runstack.pro/api/mcp (Streamable HTTP, stateless)
  • Auth: header X-RunStack-Key: rsk_... (or Authorization: Bearer rsk_...)
  • Free key: https://runstack.pro/account — 200 calls/day
  • Registry name: pro.runstack/checks

Tools

ToolWhat it checks
check_tlsCertificate validity and chain, expiry, hostname, TLS 1.0–1.3, ciphers, HSTS
check_httpStatus, redirect chain, security headers (HSTS, CSP, X-Frame-Options…), caching, compression
check_email_domainMX, SPF (10-lookup limit), DKIM, DMARC, PTR/FCrDNS, STARTTLS, MTA-STS, TLS-RPT, BIMI
check_dnsAnswers from several public resolvers compared — propagation, NXDOMAIN, inconsistencies
check_portTCP ports open / closed / filtered from the internet
check_ipIP or ASN owner, prefix, PTR, RPKI, geolocation

All tools are read-only.

Example (abridged, real output)

"Check the mail setup of runstack.ru"

FAIL: Mail domain runstack.ru: critical issues
- MX: 10 mxs1.reg.ru, 20 mxs2.reg.ru
- SPF: ~all · lookups 4/10
- DMARC: p=none
- DKIM: dkim

Findings:
- [error] Multiple DMARC records
  why: _dmarc.runstack.ru has 2 v=DMARC1 records — receivers then ignore DMARC entirely. Keep one.
  how-to: https://runstack.ru/docs/fix-dmarc-p-none
- [info] SPF ~all (softfail)
  why: Soft fail — common during monitoring.
- [info] MX certificate not valid for the server name
  why: STARTTLS works, but the MX certificate doesn't match the name. Matters for MTA-STS and DANE.

Yes, that is our own domain — the check found it.

Setup

Claude Code
claude mcp add --transport http runstack https://runstack.pro/api/mcp --header "X-RunStack-Key: rsk_..."
Cursor (~/.cursor/mcp.json) / VS Code / other clients
{
  "mcpServers": {
    "runstack": {
      "url": "https://runstack.pro/api/mcp",
      "headers": { "X-RunStack-Key": "rsk_..." }
    }
  }
}
Codex (~/.codex/config.toml)
[mcp_servers.runstack]
url = "https://runstack.pro/api/mcp"
http_headers = { "X-RunStack-Key" = "rsk_..." }

Language

Diagnoses are in English on runstack.pro. Russian: https://runstack.ru/api/mcp or ?lang=ru.

Frequently asked questions

What is RunStack Checks?

External checks of TLS, HTTP headers, email domain, DNS and ports, with cause and fix

How do I install RunStack Checks?

It runs as a remote server. In Claude Code: claude mcp add --transport http runstack-checks 'https://runstack.pro/api/mcp' --header 'X-RunStack-Key: <Free API key from https://runstack.pro/account (rsk_...)>'. For other clients, paste the JSON configuration from this page into their MCP settings.

Does RunStack Checks need an API key?

Yes. It expects X-RunStack-Key, which you set in its configuration.

Is RunStack Checks open source?

Its code is public on GitHub, but the repository does not declare a standard license.

Who maintains RunStack Checks?

It is published by WithoutCowards. AI.tn lists it but does not maintain or endorse it.

From the official MCP Registry. Listing is not an endorsement: review a server's code and permissions before giving it access to your data.