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Subdomain Enum

subdomain_enum
Read-onlyIdempotent

Enumerate subdomains via passive methods: Certificate Transparency logs and DNS brute-force. Non-intrusive attack surface mapping with reliability checks.

Instructions

Discover subdomains using passive methods: Certificate Transparency logs + DNS brute-force (no active probing). Use to map organization's attack surface; non-intrusive. Response carries next_calls — capped at 5 ssl_check hints (one per first-five subdomain) so triage scales to large enumerations without token bloat; pull tail entries by name when needed. Free: 30/hr, Pro: 500/hr. Returns {domain, count, subdomains, sources, found_via_wordlist, found_via_crtsh, wildcard_status, crtsh_status, warnings, summary, next_calls}. Always check wildcard_status FIRST: 'absent' means the DNS brute-force plane was meaningful; 'present' means the zone answers every name (wildcard DNS) so wordlist results were discarded and count is a certificate-transparency LOWER BOUND — report the surface as UNKNOWN, not small, and never infer low exposure from it; 'undetermined' means a negative-control probe went unanswered, so count is unverified. Then check crtsh_status: 'ok' means the CT lookup completed (so a low count is real); 'timeout' / 'rate_limited' / 'unavailable' / 'error' means CT logs did not respond and the count is wordlist-only — the actual attack surface is likely larger, retry later or surface the limitation to the user.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
domainYesRoot domain to enumerate subdomains for (e.g. 'example.com', 'tesla.com')

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes
Behavior5/5

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

Annotations declare readOnlyHint, idempotentHint, etc. Description goes far beyond: explains response fields, wildcard_status and crtsh_status interpretation, rate limits, and how to handle partial results. No contradiction with annotations.

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

Conciseness3/5

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

Description is lengthy but well-organized with clear structure. Front-loads purpose. However, some detail about response fields could be shortened or moved to output schema documentation.

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

Completeness5/5

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

Given complexity (multiple sources, status fields, rate limits, output schema present but not covering all interpretation), description is very complete. Covers use case, method, limitations, result interpretation, and actions for partial results.

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?

Schema has one parameter (domain) with description, coverage 100%. Description does not add significant new info for the parameter beyond what schema provides, but schema already covers it well.

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

Purpose5/5

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

Description clearly states the tool discovers subdomains using passive methods (Certificate Transparency logs + DNS brute-force) and maps attack surface. Distinguishes from sibling tools by specifying the passive, non-intrusive nature.

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

Usage Guidelines4/5

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

Explicitly describes when to use (map organization's attack surface) and mentions rate limits. Does not explicitly say when not to use or list alternatives, but context is clear.

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

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