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

Annotations already cover the safety profile (readOnlyHint, destructiveHint=false, openWorldHint), so the description's remaining burden is light. It still adds value by disclosing the data source ('normalized RDAP') and enumerating the fields returned, which matters given there is no output schema; it does not cover error handling or upstream rate limits.

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?

A single sentence that front-loads the verb and resource and packs the return-field list into a parenthetical. Every element earns its place with no filler.

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 two-parameter read-only lookup with annotations covering safety, the description is nearly complete: it names the data source and the returned fields, compensating for the absent output schema. It stops short of explaining error cases or how a CIDR query differs from a single-address query.

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%, so both parameters are already documented in the schema, establishing a baseline of 3. The phrase 'IP address or CIDR block' loosely ties the ip/prefix pair together but adds no format or constraint detail beyond what the schema states.

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 ('look up') and resource ('normalized RDAP allocation data') scoped to an IP address or CIDR block, with a parenthetical enumerating the returned fields. It is clearly distinguishable from domain-oriented siblings, though it never names or contrasts them directly.

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?

Usage is implied by the resource itself — use this when you have an IP or CIDR and need allocation info. There is no explicit when-not guidance and no mention of when asn-lookup, domain-lookup or entity-lookup would be the better choice.

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