reverse_dns

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

Despite no annotations, the description discloses key traits: read-only, no API key, rate-limited, and the return values (PTR hostname, FCrDNS pass/fail, provider guess). Lacks details on error scenarios or edge cases, but sufficient for most use cases.

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?

Single, well-structured paragraph. Front-loaded with the main action, then details, usage guidance, and notes. Every sentence serves a purpose with no redundancy.

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 tool without output schema, the description fully covers functionality, usage context, return values, and sibling differentiation. No gaps identified.

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 a descriptive parameter comment. The description adds the constraint 'Must be an IP, not a hostname', which goes beyond the schema and prevents misuse.

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 clearly states it resolves PTR records and verifies FCrDNS, with a specific verb ('resolve') and resource ('PTR record'). It distinguishes itself from the sibling tool 'asn_lookup' by specifying when to use each.

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?

Explicitly provides use cases ('validate mail-server rDNS or identify a single IP's host') and alternatives ('Use asn_lookup instead for network/BGP ownership'). Also notes read-only nature, no API key requirement, and rate limiting.

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