Free public API. Enumerate subdomains for a target domain via Certificate Transparency logs + DNS resolution.
| Name | Required | Description | Default |
|---|---|---|---|
| domain | Yes | Apex domain to enumerate. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, openWorld, idempotent, and non-destructive hints. The description adds the mechanism (CT logs + DNS resolution) and 'Free public API' status, giving the agent expectations about how results are gathered and potential limitations (e.g., reliance on CT logs). This goes beyond the annotations.
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?
The description is extremely concise: two sentences conveying purpose, scope, and method with no redundant or filler content. The key information is front-loaded.
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?
Given the simple single-parameter tool with comprehensive annotations, the description covers the essential context: what it does, how it does it, and a note on accessibility. It stops short of specifying the return format (e.g., list of subdomains with IPs), but this is not critical given the tool's simplicity.
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 coverage is 100% with the 'domain' parameter clearly described as 'Apex domain to enumerate.' The tool description mostly repeats 'target domain' and adds no additional parameter semantics beyond what the schema already provides. Baseline of 3 is appropriate.
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?
The description states a specific verb ('Enumerate') and resource ('subdomains') with a clear target ('a target domain') and method ('via Certificate Transparency logs + DNS resolution'). This uniquely distinguishes it from all sibling tools, which focus on individual record types, WHOIS, or status checks.
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 description provides clear context for when to use the tool: when subdomain enumeration is needed. It also notes it is a 'Free public API,' indicating no authentication barrier. While it does not explicitly mention alternatives or exclusions, the uniqueness among siblings makes the use case apparent.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Multiple tools operate in the same DNS/domain space, e.g., generic DNS record lookup overlaps with specific CNAME, TXT, SPF, DKIM, and DMARC lookups. Website status checker also overlaps with SSL check and redirect checker, though descriptions clarify their distinct purposes.
All tool names follow a consistent snake_case pattern with a 'tools_' prefix and an action word at the end (lookup, checker, check, finder). This makes the naming highly predictable and uniform.
16 tools is slightly above the ideal 3-15 range, but the domain intelligence scope is broad enough that each tool addresses a specific need without feeling bloated. The count is reasonable for a comprehensive domain/DNS toolkit.
The tool set covers a wide range of domain-related functionality: DNS records, email authentication (SPF, DKIM, DMARC), SSL/TLS, HTTP headers, redirects, WHOIS, availability, subdomain enumeration, and website status. No obvious critical gaps exist for its apparent purpose.
