asn_lookup

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

With no annotations provided, the description carries the full burden. It discloses the backend service (Team Cymru's whois), notes that no API key or GeoIP database is needed, and constrains inputs. However, it does not describe the output shape, pagination, or failure behavior, and does not explicitly state that this is a read-only 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?

Three tight sentences with no filler. The core purpose is front-loaded, the service fact and input constraints follow naturally, and every sentence 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?

For a single-parameter lookup tool with no output schema and no annotations, the description is quite complete: it gives the service, the accepted input forms, the exclusions, and the fallback resolution path. The only clear gap is the exact return structure, though the purpose line already hints at ASN, country code, and org info.

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 only provides 'target' with no description (0% coverage), so the description must compensate. It does: it explains that target can be an IP literal, an ASN like AS15169, or a bare number like 15169, and clarifies what is not acceptable (hostname). This adds real meaning 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?

The description names a specific verb+resource: 'ASN + country-code lookup for an IP, or org info for an AS number'. It immediately tells the agent what the tool does and distinguishes it from sibling tools like dns_lookup 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?

Explicitly states the input domain: takes an IP literal or AS number, not a hostname, and directs the agent to 'resolve first with dns_lookup if you only have a name'. This gives clear when-to-use guidance and names the alternative.

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