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

With no annotations provided, the description carries the full behavioral burden and does well: it discloses data sources, return structure (IPv4/IPv6 prefixes with sample), that it is keyless and free at the source, and the pricing model ($0.005 per call via x402 USDC). It does not disclose rate limits, caching, or failure modes like missing RDAP records.

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 a single dense but well-structured sentence that front-loads the data sources and follows with workflow context and pricing. It is appropriately sized for the amount of information conveyed, though slightly information-dense.

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, covering data sources, output shape, pricing, and usage context. It could be improved by mentioning error handling or what happens when an ASN is not found, but the core is solid.

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 the schema already documents the single 'asn' parameter with format examples ('15169 or AS15169'). The description adds no further parameter detail. Baseline 3 applies when the schema fully covers parameters.

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 states a specific verb (lookup) and resource (autonomous system number) and enumerates the exact data sources and fields returned (RDAP registry record via ARIN-to-RIR referral, Team Cymru DNS, RIPEstat prefixes split IPv4/IPv6). It clearly distinguishes itself from sibling red_ip by naming the workflow relationship ('natural second call after /v1/red/ip').

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 provides clear context for when to use it: after red_ip yields an origin ASN. It also notes it is keyless and free at the source. However, it does not explicitly state when NOT to use it or list alternative ASN-related tools, though none appear in the sibling list.

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