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

Annotations already declare readOnly, idempotent, openWorld and non-destructive, so the safety profile is covered. The description adds genuinely non-structured context: the metered pricing model (a few free samples per day, then $0.002 USDC per call via x402), which materially affects how an agent should budget or batch calls. It stops short of describing latency, rate-limit behaviour, or failure modes on unallocated IPs.

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?

Two tight sentences with zero waste: the return payload is front-loaded, then the cost caveat. Every clause earns its place and there is no boilerplate.

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?

With an output schema present, the description need not explain return values, and it correctly focuses on source and cost. An agent has enough to call it correctly: one required IP argument, a read-only idempotent profile, and the payment model. The only real gap is the absence of any hint about overlap with the ip-geolocation siblings.

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?

There is a single parameter and schema coverage is 100%, so the schema already carries the full burden (type plus 'IPv4 or IPv6 address'). The description adds no format, syntax, or edge-case detail about the ip argument. Baseline 3 is appropriate when the schema does the work and the description contributes nothing extra.

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 resource and enumerates exactly what is returned (network, organisation, range, country, abuse email) plus the data source (regional internet registry). An agent can tell what it gets back without opening the schema. It does not explicitly differentiate itself from the near-namesake siblings ip-geolocation__lookup or ip-geolocation__asn, so it falls short of a 5.

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 says what the tool returns but never says when to use it versus ip-geolocation__lookup, ip-geolocation__asn, or domains__abuse-contacts — siblings that plausibly overlap on IP and abuse-email data. The only usage-adjacent content is the pricing model, which is a cost signal rather than selection guidance.

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