Check hostnames for subdomain takeover using DNS records and optional HTTP probes to identify dangling records before attackers exploit them.
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.
v0.1.5Input schema / $schemaPrevious value: -"http://json-schema.org/draft-07/schema#"New value: +"https://json-schema.org/draft/2020-12/schema"v0.1.1Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations exist, so the description carries the full disclosure burden, and it discloses almost nothing: it never says the tool performs live network resolution/HTTP fetches, gives no timeout or rate-limit expectations, and doesn't mention the 200-host batch cap or whether a probe failure invalidates a result. The only hint of network activity ('Fetch pages') lives in the schema, not the description.
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 tight sentence with the action front-loaded and no filler. It is efficient, though slightly under-specified for a tool that performs active probing.
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?
For a simple two-parameter tool with full schema coverage, this is minimally adequate. But with no output schema and no annotations, the description still leaves the agent guessing what comes back (per-host verdicts, fingerprints, findings?) and doesn't warn that the default httpProbe=true triggers outbound page fetches.
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 schema already documents both hosts and httpProbe (including its default of true). The description only adds the source of hostnames (DNS zone, certificate logs), which is mild but real value beyond the schema; baseline 3 applies.
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 (check) plus the resource (specific hostnames) and the exact condition being tested (subdomain takeover), which separates it from sibling DNS tools like lookup_dns or enumerate_subdomains. It does not explicitly name those siblings, so it stops short of a 5.
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 input hostnames come from, giving an implied workflow (enumerate, then check). It never says when to prefer this over dns_intelligence__lookup_dns or enumerate_subdomains, and states no exclusions or prerequisites.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.