reverse_dns

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

With no annotations, the description carries the behavioral burden. It states the operation is a PTR lookup and that the result is the mapped name 'if any', which covers the core behavior. It does not disclose response format, error behavior for invalid IPs, or what happens when no PTR record exists.

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 a single focused sentence with no filler. It front-loads the core verb and adds useful scope details ('IPv4 or IPv6', 'if any') without wasting words.

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 one-parameter, read-only DNS utility with no output schema, the description covers the input domain and the general return value. The only gaps are explicit failure/response formatting details, which are minor given how simple the operation is.

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 provides only a bare 'ip' string with no description, and the description compensates by specifying that it accepts an IPv4 or IPv6 address and that the lookup maps that address to a name. It lacks format examples or edge-case constraints, but for a single simple parameter this is adequate.

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 names a specific operation ('PTR lookup') and clarifies the direction of the mapping ('what name the address maps back to'). This clearly distinguishes reverse_dns from sibling tools like dns_lookup, even without naming them explicitly.

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 implies this tool is for IP-to-name lookup rather than name-to-IP lookup, which is sufficient context given the sibling list. However, it does not explicitly state when to prefer this tool over dns_lookup or other alternatives, leaving usage decisions to inference.

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