Check hostnames for subdomain takeover by validating DNS records and optional HTTP fingerprints, revealing dangling DNS targets.
Check specific hostnames (e.g. from your DNS zone or certificate logs) for subdomain takeover
| Name | Required | Description | Default |
|---|---|---|---|
| hosts | Yes | Hostnames to check, e.g. ["blog.example.com"] | |
| httpProbe | No | Fetch pages to match takeover fingerprints (default: true) |
Changes observed during successful MCP inspections.
v0.1.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden. It says nothing about whether checks perform network requests, how long they take, rate/permission requirements, or that only the 200-host cap applies; the httpProbe fetching behavior is disclosed only in the schema, not here.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
A single front-loaded sentence with no filler; the parenthetical example earns its place. It is short but could have absorbed one more clause of substance at negligible length cost.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
With no annotations and no output schema, the description must carry the operational context, yet it omits what a result contains, whether checks are safe/read-only, the batch limit, and any latency implications of HTTP probing. For a 2-parameter security-scan tool this leaves real gaps.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema description coverage is 100%, so the baseline is 3. The description adds only that the hostnames are 'specific' and come from DNS zones or certificate logs; it never mentions the httpProbe toggle or the 1-200 host bounds, so it does not go beyond the schema.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
States a specific verb and resource: 'Check specific hostnames ... for subdomain takeover'. The security intent (subdomain takeover) is distinctive and separates it from sibling lookup/enumeration tools, though no sibling is named explicitly.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The parenthetical '(e.g. from your DNS zone or certificate logs)' implies where the host list comes from, which hints at when to use it. However, it never states when to prefer this over enumerate_subdomains, lookup_dns, or audit_domains, nor any exclusion conditions.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.