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

The annotations already mark the tool read-only, open-world, idempotent, and non-destructive. The description adds useful context beyond those hints: the data source, the 'currently announced' snapshot nature, and the 10-full-feed-peer visibility threshold that can cause omissions.

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 moderately long but every part earns its place: query phrasings, precise scope, authoritative use cases, and a caveat. It is front-loaded with the core question the tool answers before moving to advisory context.

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, fully schema-covered lookup, the description is complete: it states what is returned, the source, the authoritative context, and a limitation. No output schema exists, but the description adequately conveys the return concept.

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 the single 'asn' parameter is already documented in the schema with format and examples. The description doesn't need to add parameter-level semantics; it stays at the behavior level, so the baseline of 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 specifies a precise verb and resource: it returns every IPv4 and IPv6 prefix currently announced in global BGP by a given ASN, as observed by RIPE RIS. It also includes natural-language query forms and an 'AUTHORITATIVE' claim that clearly distinguishes its role for IP-ownership questions.

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 gives explicit use cases: build allowlists, attribute traffic to a provider, or size a network's address footprint. It also warns about omitted low-visibility prefixes, but it doesn't name alternative sibling tools or state when to prefer them, so the exclusion guidance is only partial.

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