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

With no annotations, the description carries the full burden and does well: it discloses billing behavior ($0.0033 via x402), that private ranges are refused before payment, and that no charge applies if registries fail — non-obvious, agent-relevant economics. It omits latency, rate limits, or error-surface detail, keeping it short of a 5.

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?

Front-loaded with the purpose and output inventory, followed by short sentences on refusal, failure credits, and price. Dense but largely waste-free; the parenthetical license attribution is a slight detour but is required for the data source.

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 3-parameter read-only lookup with no output schema and no annotations, the description covers inputs, outputs (network, size, membership, holder, ASN, country), failure behavior, and cost. Only the shape/format of returned fields is left implicit, which is acceptable given no output schema exists.

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 all three parameters (query, check, request_id) are fully documented in the schema. The description adds only indirect hints ('One ... IP or CIDR in', 'membership checks') and nothing about the request_id idempotency semantics, so it does not meaningfully exceed the schema baseline.

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 and resource — takes one public IP or CIDR and returns a normalized network, size, membership results, holder, abuse contact, origin ASN, and country. It enumerates the concrete outputs and names the underlying sources (RIR RDAP, RIPEstat, DB-IP Lite), so an agent can distinguish it from every sibling (url_normalize, email_check, phone_normalize all operate on other input types).

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 constraint 'One public IP or CIDR in' and 'Private ranges refused before payment' clearly delimit valid input and state a when-not condition. It doesn't name alternative tools to use instead (e.g., for OSINT graph work), so it stops short of explicit routing, but the applicability context is clear.

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