Subdomain Scan1 MCP Server

get_subdomains

Enumerate and discover all subdomains for a given domain by querying the Subdomain Scan1 API, returning results in JSON format.

Instructions

Enter a domain here and we'll check and return all subdomains in a JSON format for you.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "domain": "<domain>"
    },
    "name": "get_subdomains"
  }
}

Input Schema

Name	Required	Description	Default
`domain`	Yes	Example value: rapidapi.com

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.0Feb 9, 2026

TDQS

C2.9/5.0

Behavior2/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

No annotations are provided, so the description carries the full burden. It mentions the tool will 'check and return' subdomains, implying a read-only operation, but doesn't disclose behavioral traits like rate limits, authentication needs, data sources, or whether it performs active scanning vs. cached lookups. For a tool with no annotations, this is insufficient.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single, clear sentence that efficiently states the action and output. It's front-loaded with the core purpose and avoids unnecessary details. However, it could be slightly more structured by separating usage from output format, but it's still highly concise.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's low complexity (1 parameter, no annotations, no output schema), the description is minimally adequate. It covers the basic purpose and output format, but lacks details on behavioral aspects and doesn't explain the return values beyond 'JSON format'. For a simple tool, it meets the minimum but leaves gaps in transparency.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The input schema has 100% description coverage, with the 'domain' parameter documented as 'Example value: rapidapi.com'. The description adds minimal value beyond this, only reinforcing that you 'Enter a domain here'. With high schema coverage, the baseline is 3, as the description doesn't significantly enhance parameter understanding.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose: 'check and return all subdomains' for a given domain. It specifies the verb ('check and return') and resource ('subdomains'), and mentions the output format ('JSON format'). However, it doesn't differentiate from siblings since there are none, so it can't achieve a perfect 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides minimal guidance: 'Enter a domain here' implies usage when you have a domain to analyze. However, it lacks explicit when-to-use scenarios, alternatives (though none exist), or exclusions. It's basic usage instruction rather than strategic guidance.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

Deploy Server

Other Tools

get_subdomainsC