reverse_dns_lookup

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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds behavioral context beyond annotations: it supports batch queries, returns all known hostnames per IP, and provides clear indication when none are found. This is useful operational detail that the schema and annotations do not convey.

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?

Two sentences, no filler. The first sentence states the core purpose, the second adds batch and return details. Information is front-loaded and every word earns its place.

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?

This is a simple one-parameter tool with a clear return description. The description explains what the tool does, how it handles multiple IPs, and what it returns (hostnames and a not-found indication). Annotations cover read-only and open-world aspects. Nothing essential for correct invocation is missing, even without an output schema.

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 description coverage is 100%, with the ips parameter clearly documented as a list of IP addresses. The description adds no new semantic meaning—'batch lookups' is implied by the array type. Per the baseline rule for high coverage, a 3 is appropriate; the description does not compensate or add value beyond the schema.

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 action (perform reverse DNS lookups), a clear resource (IP addresses), and the expected output (hostnames). It also distinguishes itself from forward DNS lookups by the term 'reverse,' which is reinforced by the sibling dns_lookup. This is unambiguous and not a tautology.

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 usage for IP-to-hostname resolution but does not explicitly contrast with alternatives like dns_lookup or ip_lookup. It mentions batch support, which is a feature, but offers no when-to-use/when-not-to-use guidance. Usage is inferred from the tool name and context rather than stated.

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