asn_lookup

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

No annotations are provided, so the description carries the full burden. It mentions that no API key is needed, which is useful, but does not disclose potential behaviors like rate limits, data freshness, or whether the tool is read-only. The description is adequate but lacks depth.

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 only two sentences, front-loaded with the core purpose, and every sentence adds value. No wasted words or redundancy.

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?

Given the tool's simplicity (one parameter) and the presence of an output schema, the description covers the essentials: purpose, usage, and a key constraint. It could mention IPv6 support or limits, but it is largely complete for a straightforward lookup tool.

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?

With 100% schema coverage, the baseline is 3. The description adds context about the data source and service ('using Team Cymru WHOIS') but does not significantly enhance the parameter meaning beyond what the schema already provides ('Domain or IP address').

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 explicitly states the tool's action ('Find the Autonomous System Number (ASN) and network ownership') and target ('domain or IP'), making the purpose very clear. It also specifies the data source (Team Cymru WHOIS), which helps distinguish from sibling tools like 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?

The description includes a usage hint ('Useful for identifying hosting provider and network ownership') and a key constraint ('No API key required'). It does not explicitly exclude alternatives, but the context is sufficient for most agents to decide when to use this tool.

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