Subdomain API

What the Subdomain API MCP server does

Subdomain API MCP server provides domain-level subdomain discovery through passive data. Given a domain, it can return known subdomains or report how many are known. The available description does not identify a particular DNS provider, search engine, or other external data source behind the service.

This makes the service relevant to reconnaissance, asset inventory, and preliminary domain research. It is focused on discovering names associated with a domain, not on managing DNS records or changing domain configuration. No evidence is provided that it performs active scanning, validates hosts, or checks whether each result currently resolves.

Tools and capabilities

The documented capabilities are narrow:

• Find known subdomains for a domain.
• List discovered subdomain entries.
• Count the known entries for a domain.
• Include passive results that may contain historical subdomains.

The listing does not provide formal tool names, argument schemas, response examples, pagination behavior, filtering options, or error formats. Treat the operations above as the supported functional scope rather than assuming additional controls.

For agents, the useful distinction is between retrieval and measurement. Listing supports workflows that need the actual names, while counting supports quick inventory checks or comparisons without requiring the full result set. The material does not say whether one request can perform both operations or whether results include metadata such as discovery dates, source records, or status.

Limitations and notes

Subdomain API MCP server uses passive information, so its output should not be interpreted as a complete or live view of a domain's infrastructure. Known data can be incomplete, stale, or historical. A returned name may no longer be configured, and a name that is currently in use may not appear in the results.

The supplied material does not document authentication, rate limits, supported transports, installation commands, environment variables, client compatibility, licensing, or deployment requirements. It also does not state whether the service accepts apex domains only, how it handles malformed input, or whether wildcard and nested subdomains receive special treatment.

Before using the results for operational decisions, independently confirm the records and their current status. For an inventory workflow, preserve the distinction between a discovered name and a verified active host. For a counting workflow, document that the number represents known passive entries, potentially including historic data, rather than a guaranteed count of live subdomains.

The Subdomain API MCP server is therefore best evaluated as a focused passive-discovery source. It fits tasks that need names or counts from existing data; the available description does not support claims about active enumeration, DNS mutation, monitoring, or exhaustive coverage.