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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, open-world), and the description layers on genuinely useful behavior: exact free-tier quotas (500/day per client IP, 60/min), the auth mechanism for higher limits, and the critical semantic caveat that the 0-100 score is not an attack probability. That last point is the kind of interpretation guidance annotations cannot express.

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?

Front-loaded with purpose, then return contents, then the score caveat, then operational limits — a sensible order with no filler sentences. The pricing URL is the only element that is marginally promotional rather than operational.

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 no output schema, the description carries the burden of describing return values and does so concretely (score, evidence state, network, geo). Combined with quota and auth details, an agent has everything needed to call and interpret the tool correctly.

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 a single parameter and 100% schema description coverage (including IPv4/IPv6 examples), the schema already carries the parameter semantics. The description repeats the IPv4/IPv6 scope but adds no format or edge-case detail beyond what the schema states, so baseline 3 applies.

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 verb and resource ('Look up the risk profile and geolocation of an IPv4 or IPv6 address') and immediately scopes the return payload (risk score, evidence state, ASN/usage type, geographic attribution). There are no siblings to disambiguate from, and the description leaves no ambiguity about what the tool produces.

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?

Usage context is clear and practical: the rate-limit tiers and the X-API-Key header tell the agent exactly what it needs to call this at scale, and the score caveat tells it how to interpret results. It stops short of explicit when-to-use/when-not guidance, though no alternative tools exist to route against.

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