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

Annotations already declare readOnlyHint and openWorldHint, so safety is covered. The description adds genuinely useful context beyond them: the per-call price of $0.002 USDC via x402, which materially affects an agent's decision to call it, plus the dual-mode behavior. It still omits any mention of rate limits or failure behavior.

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?

One dense but well-ordered sentence front-loads the operation, then branches cleanly by input type, then gives the classification use case, then the cost. Every clause earns its place with no filler.

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, read-only lookup with no output schema and annotation coverage already in place, the description tells the agent both input modes, the returned fields, the use case, and the price. Only edge behavior (invalid input, empty results, rate limits) is unaddressed, which is a minor gap at this complexity.

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 `q` param is documented as "IP address or AS number". The description does clarify what each accepted input form yields downstream, which is useful, but it adds no syntax, format, or validation detail beyond what the schema states. Baseline 3 applies when the schema carries the load.

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 (routing lookup) and resource (IP/ASN) and enumerates the exact fields returned for each of the two input modes, so an agent knows precisely what it gets. It stops short of a 5 because it never distinguishes itself from the adjacent sibling `ip`, which an agent could plausibly confuse it with for IP lookups.

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?

"Identify hosting providers, clouds and ISPs" implies the intended use case, and the dual IP/AS-number framing hints at when each mode applies. But there is no explicit when-to-use, no when-not, and no named alternative (e.g. `ip` for pure geolocation), leaving the routing between siblings to inference.

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