Free public API. Reverse-DNS (PTR) lookup for an IP address. Returns one or more hostnames if configured.
| Name | Required | Description | Default |
|---|---|---|---|
| ip | Yes | IPv4 or IPv6 address, e.g. 8.8.8.8. |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare read-only and non-destructive hints. The description adds useful context by stating it is a 'Free public API' and noting 'if configured' to indicate hostnames may not exist, which goes beyond the annotations without contradicting them.
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 two short sentences, front-loaded with the core functionality, and contains no wasted words. 'Free public API' is superfluous but does not detract from the conciseness.
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 single-parameter read-only lookup, the description covers the purpose, return type ('one or more hostnames'), and a caveat ('if configured'). With no output schema, this is sufficient for an agent to understand what the tool does and what it returns.
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?
The schema fully describes the 'ip' parameter with type, minimum length, and an example. The description does not add extra semantic detail beyond referencing the IP address in context. Since schema coverage is 100%, the 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 uses a specific verb 'lookup' with a clear resource (IP address) and explicitly states the return value (hostnames). It clearly distinguishes this tool from sibling DNS lookup tools that perform forward lookups.
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 clearly indicates this tool is for reverse-DNS (PTR) lookups, providing clear context for when to use it. It does not explicitly mention alternatives or exclusions, but the purpose is unambiguous and self-evident.
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.
