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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false, so the safety profile is covered. The description's field list is effectively return-value disclosure (valuable since there is no output schema), but it says nothing about rate limits, lookup latency, or why idempotentHint is false for a read operation.

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, zero filler, with the capability front-loaded and the usage trigger immediately after. Every clause 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?

With no output schema, the description usefully previews the returned fields, and annotations cover the safety profile. The only real gap is that neither the description nor the schema explains behavior when both parameters are supplied or when neither 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?

Schema coverage is 100% and both parameters are self-documenting with format examples. The description implies the two inputs are alternative query modes but never states whether ip and asn are mutually exclusive or which is required, adding little 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?

States a specific verb+resource ('IP address or AS number lookup') and enumerates the returned data (holder, announced prefixes, origin AS, country, RPKI status, abuse contact). This clearly separates it from siblings like domain, company, or sanctions 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?

'Use when: you need to know who runs an IP address or network' gives a clear trigger condition. It stops short of naming when NOT to use it or pointing to a sibling (e.g. domain) for hostname-based questions.

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