# Subdomain Finder MCP (remote · subdomain-finder-mcp.lipmichal.workers.dev)

Passive subdomain enumeration from certificate transparency (certspotter, crt.sh) with DNS checks.

- Trust score: 66/100 (medium)
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-11-05

## Components

- remote · `subdomain-finder-mcp.lipmichal.workers.dev`: 66/100 (this document), [markdown](https://verifymcp.io/servers/theluckystrike-subdomain-finder-mcp/subdomain-finder-mcp.md), [page](https://verifymcp.io/servers/theluckystrike-subdomain-finder-mcp/subdomain-finder-mcp)

## Channel facts

- Endpoint: `https://subdomain-finder-mcp.lipmichal.workers.dev/mcp`
- Transports: `streamable-http`
- Auth: `none`
- Version: `1.0.0`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-11-05.

- **Endpoint Security**: 63/100
  - The endpoint's TLS certificate is valid, in date, and uses a strong key.
  - No authorisation is required to call this server. Nothing on it is marked destructive, but we can't show that an anonymous caller can only read: full credit needs the server to list at least one tool and every tool to be verifiably read-only. We use a best-effort check of tool names and descriptions to tell read-only tools from tools that change things, so some genuinely read-only tools may not get full credit. Names that start with a read verb (get, list, read, search and similar) and accurate readOnlyHint annotations help. Meet that to earn full credit, or require authorisation.
  - HTTPS enforcement could not be verified: the plaintext port answered with HTTP 405, which proves neither a plaintext path nor enforcement.
  - HSTS check failed: the Strict-Transport-Security header is absent.
  - DNSSEC check failed: this domain isn't protected by DNSSEC.
- **Transport & Reachability**: 100/100
  - Verified streamable-http transport via a live MCP handshake.
- **Schema Quality & AI Usability**: 63/100
  - AI-judged instruction clarity (good).
  - Context-footprint check failed: tool/resource definitions use about 960 tokens (~240/item across 4 items; 4 tools + 0 resources), over budget; trim descriptions and params.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 10/100
  - Stability observed for 3 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 100/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 100% of tool parameters carry a description.
- **Tool Safety**: 100/100
  - No prompt-injection markers were found in the server instructions, tool names or descriptions we captured.
  - We read all 4 captured tool definition(s), and no name or description among them implies an irreversible operation.
  - An AI judge read all 5 captured unit(s) of tool text and found none that tries to manipulate the model reading it.
- **Capabilities**: 100/100
  - Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.

## Install

### How do I install the Subdomain Finder MCP server?

Subdomain Finder MCP is a hosted endpoint at https://subdomain-finder-mcp.lipmichal.workers.dev/mcp, so there is nothing to install locally. Ready-made configuration for Claude, Cursor, VS Code, Codex and 5 more is on this page, copied from each client's own documentation.

### Claude

```bash
claude mcp add --transport http theluckystrike-subdomain-finder-mcp 'https://subdomain-finder-mcp.lipmichal.workers.dev/mcp'
```

### Cursor

```json
{
  "mcpServers": {
    "theluckystrike-subdomain-finder-mcp": {
      "url": "https://subdomain-finder-mcp.lipmichal.workers.dev/mcp"
    }
  }
}
```

### VS Code

```json
{
  "servers": {
    "theluckystrike-subdomain-finder-mcp": {
      "type": "http",
      "url": "https://subdomain-finder-mcp.lipmichal.workers.dev/mcp"
    }
  }
}
```

### Codex

```toml
[mcp_servers.theluckystrike-subdomain-finder-mcp]
url = "https://subdomain-finder-mcp.lipmichal.workers.dev/mcp"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "theluckystrike-subdomain-finder-mcp": {
      "type": "remote",
      "url": "https://subdomain-finder-mcp.lipmichal.workers.dev/mcp",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add theluckystrike-subdomain-finder-mcp --url 'https://subdomain-finder-mcp.lipmichal.workers.dev/mcp' --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  theluckystrike-subdomain-finder-mcp:
    url: "https://subdomain-finder-mcp.lipmichal.workers.dev/mcp"
```

### Netclaw

```json
{
  "McpServers": {
    "theluckystrike-subdomain-finder-mcp": {
      "Transport": "http",
      "Url": "https://subdomain-finder-mcp.lipmichal.workers.dev/mcp"
    }
  }
}
```

### Vellum

```bash
assistant mcp add theluckystrike-subdomain-finder-mcp -t streamable-http -u 'https://subdomain-finder-mcp.lipmichal.workers.dev/mcp'
```

### Other

```json
{
  "mcpServers": {
    "theluckystrike-subdomain-finder-mcp": {
      "type": "http",
      "url": "https://subdomain-finder-mcp.lipmichal.workers.dev/mcp"
    }
  }
}
```

The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-11-04 (score 66, +1)

No change was recorded against any check on this day. Stability & Change Management went from 3 to 7. That category is still filling its 30-day observation window: 1 days of observed history at the previous scan, 2 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-11-03 (score 65, 0)

- [functional improvement] Stability: unverified → 0.03

### 2026-11-02 (score 65)

First indexed and scored.

## MCP tools (4)

### `find_subdomains` (~290 tokens)

Find subdomains (certificate transparency)

Passive subdomain enumeration for a domain from live certificate transparency logs: certspotter (unexpired certificates) with crt.sh as fallback or for expired history. Returns deduplicated hostnames with first seen and last seen issuance dates, certificate count, issuers and whether a wildcard certificate covers the name, plus the list of wildcard entries. Set resolve=true to also check the first 40 names with DNS over HTTPS and mark live hosts. Passive lookup of public certificate transparency logs; nothing is sent to the target. Use it on assets you own or are authorised to test.

Input parameters:

- `domain` (string, required): Registered domain, for example "example.com". A URL is accepted and reduced to its host.
- `include_expired` (boolean): Also include names from expired certificates (uses crt.sh). Finds retired hosts; slower.
- `limit` (integer): Max hostnames returned (1-1000). Totals are always reported.
- `max_pages` (integer): certspotter pages to read (1-5). Each page is one request against its keyless rate limit.
- `resolve` (boolean): Also resolve up to 40 of the returned names over DNS (newest first).
- `source` (string): auto = certspotter first (fast, unexpired certificates), crt.sh if it fails or throttles. crtsh = crt.sh only (includes expired with include_expired).

### `resolve_subdomains` (~176 tokens)

Resolve subdomains (DNS over HTTPS)

Resolve up to 40 hostnames now through Cloudflare DNS over HTTPS (A, AAAA and the CNAME chain). Each host is marked live, nxdomain, no_records or dangling_cname (a CNAME whose target does not exist, a subdomain takeover lead), and CNAME targets on cloud platforms (S3, Azure, Heroku, GitHub Pages, Netlify, Vercel and others) are named. Also probes a random label per parent domain to detect wildcard DNS. DNS lookups only; no connection is made to the hosts.

Input parameters:

- `check_wildcard` (boolean): Probe one random label under each parent domain (max 3) to detect wildcard DNS.
- `hosts` (array, required): Hostnames, for example ["www.example.com", "api.example.com"]. Max 40.

### `get_certificate_history` (~222 tokens)

Get certificate history for a host

Certificates logged in certificate transparency for one hostname (or a whole domain with include_subdomains): issuer organisation and DN, not_before and not_after dates, every SAN on the certificate, revocation status and SHA-256 where certspotter has them. Summarises first and last issuance and the issuers used, which shows CA changes and renewal cadence. Default source certspotter (unexpired); include_expired uses crt.sh for the full history.

Input parameters:

- `host` (string, required): Hostname, for example "api.example.com" or "example.com".
- `include_expired` (boolean): Also include names from expired certificates (uses crt.sh). Finds retired hosts; slower.
- `include_subdomains` (boolean): Also include certificates for names under the host.
- `limit` (integer): Max certificates returned, newest first (1-100).
- `source` (string): auto = certspotter first (fast, unexpired certificates), crt.sh if it fails or throttles. crtsh = crt.sh only (includes expired with include_expired).

### `summarize_attack_surface` (~191 tokens)

Summarize attack surface from CT

Reads a domain's subdomains from live certificate transparency and groups them for recon triage: development and test, staging, admin and internal tools, APIs, authentication, mail, remote access (VPN), storage and CDN, legacy and backup. Each group has a count, examples and why it matters. Also returns naming clusters (for example *.eu.example.com), certificate issuers in use, wildcard entries and the 10 newest names. Passive only.

Input parameters:

- `domain` (string, required): Registered domain, for example "example.com". A URL is accepted and reduced to its host.
- `include_expired` (boolean): Also include names from expired certificates (uses crt.sh). Finds retired hosts; slower.
- `source` (string): auto = certspotter first (fast, unexpired certificates), crt.sh if it fails or throttles. crtsh = crt.sh only (includes expired with include_expired).

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/theluckystrike-subdomain-finder-mcp/subdomain-finder-mcp#diagnostics

## Score history

- 2026-11-05: 66
- 2026-11-04: 66
- 2026-11-03: 65
- 2026-11-02: 65

## Common questions

### What is the Subdomain Finder MCP server?

Subdomain Finder MCP is listed in the public MCP registry as io.github.theluckystrike/subdomain-finder-mcp. Passive subdomain enumeration from certificate transparency (certspotter, crt.sh) with DNS checks. This page covers its hosted endpoint (https://subdomain-finder-mcp.lipmichal.workers.dev/mcp).

### Is the Subdomain Finder MCP server safe to use?

Subdomain Finder MCP scores 66 out of 100 on VerifyMCP. That is a record of what we were able to check automatically, not an endorsement. The category breakdown on this page shows every signal behind the number, including the ones we could not confirm.

### What tools does the Subdomain Finder MCP server expose?

Subdomain Finder MCP exposes 4 tools: find_subdomains, resolve_subdomains, get_certificate_history, summarize_attack_surface. Their descriptions and schemas cost roughly 879 tokens of context every time the server is loaded.

### Does the Subdomain Finder MCP server require authentication?

No. We connected to Subdomain Finder MCP without credentials and it answered, so anything it exposes is reachable by anyone who knows the address.

### Is the Subdomain Finder MCP server still maintained?

Subdomain Finder MCP is still listed as active in the MCP registry. We last reached this channel on 5 November 2026. Those dates come from our own scans of the registry and the channel itself, not from anything the publisher announced.

### What did VerifyMCP test on the Subdomain Finder MCP server?

VerifyMCP ran 12 checks on Subdomain Finder MCP, covering TLS certificate, Authorization, HSTS header, DNSSEC and 8 more. One item could not be completed, a gap on our side rather than a finding about Subdomain Finder MCP: HTTPS. Supply Chain Security and Provenance & Transparency do not apply to a hosted endpoint, so they were not tested. The score does not measure everything, and the scoring documentation lists what it leaves out.

## Links

- Remote endpoint: https://subdomain-finder-mcp.lipmichal.workers.dev/mcp
- Repository: https://github.com/theluckystrike/subdomain-finder-mcp
- Website: https://bugbountyreality.com/tools/subdomain-finder-real/
- Changelog RSS feed: https://verifymcp.io/servers/theluckystrike-subdomain-finder-mcp/subdomain-finder-mcp.xml
- Changelog JSON feed: https://verifymcp.io/servers/theluckystrike-subdomain-finder-mcp/subdomain-finder-mcp/changelog.json
- Trust report (JSON): https://verifymcp.io/servers/theluckystrike-subdomain-finder-mcp/subdomain-finder-mcp.json
- HTML version of this page: https://verifymcp.io/servers/theluckystrike-subdomain-finder-mcp/subdomain-finder-mcp