Hosted Domains (reverse IP)

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

With no annotations provided, the description carries the full burden. 'List' and 'lookup' strongly imply a read-only operation with no destructive side effects, which is transparent enough for this type of tool. It does not disclose every nuance (e.g., rate limits), but the core safety profile is clear.

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 exactly two sentences: the first states the purpose, the second provides usage context. Every sentence earns its place, and the most important 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 tool's simplicity (2 params, no output schema, no annotations), the description covers the essential purpose and usage. It doesn't explain the return format or detailed pagination behavior, but those are inferable and the page parameter is already described in the schema. It is complete enough for an agent to use effectively.

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 already provides 100% coverage for both parameters ('ip' and 'page') with clear descriptions. The tool description adds no additional parameter-specific meaning beyond reinforcing that the IP is the target. Baseling 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 opens with 'List domain names hosted on a given IP address (reverse-IP lookup)', which uses a specific verb and resource, immediately distinguishing it from sibling tools like ip_geolocation or whois_lookup.

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?

It provides explicit usage scenarios ('investigating a suspicious host or mapping an organisation's footprint') and clearly states the tool's use case for finding other sites on the same server. However, it does not explicitly name alternatives or exclusions, so it stops short of a full 5.

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