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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds a genuinely useful behavioral detail ('approximate' location, plus the REST endpoint GET /v1/ipinfo), but says nothing about behavior on invalid/private IPs, rate limits, or response shape.

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 filler, front-loading the core action and the return fields before the endpoint reference. Everything earns its place.

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 usefully names the returned fields (country, city, coordinates), and the readOnly annotation covers the safety dimension. Minor gaps remain around invalid-IP handling and result accuracy, but nothing an agent needs in order to invoke it correctly is missing.

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 'ip' and 'lang' parameters are already fully documented in structured data, including the IPv4/IPv6 requirement. The description repeats none of the parameter semantics and does not explain how 'lang' affects results, 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 ('Look up') and resource ('location of an IP address') and enumerates what the result contains (country, city, coordinates). This is clearly distinguishable from the address-based geocode siblings, which take address strings rather than IPs.

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 is only implied: the agent must infer that this tool applies when it has an IP address instead of an address string. No explicit when-to-use, no exclusions, and no mention of when a sibling geocoder would be the right choice instead.

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