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

Annotations already declare readOnlyHint and idempotentHint, so safety is covered; the description adds the hosted-mode nuance (returns the caller's connecting IP rather than public egress) and discloses the detection categories returned. It omits auth requirements and whether the result is cached, but adds real context beyond the annotations.

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?

Three short sentences, front-loaded with the return value, then usage, then the parameter fact. Every clause carries information; nothing is redundant.

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 has to describe the return payload, and it does so at the field-category level (IP, geolocation, ASN/ISP, proxy/datacenter flags). Exact response shape and error modes are unspecified, but for a zero-parameter read tool this is close to complete.

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?

Zero parameters, so the baseline is 4. The description affirmatively states 'No parameters needed', which confirms to the agent that an empty object is correct and no filtering arguments exist.

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 ('Returns the caller's public egress IP address') and enumerates the payload (geolocation, ASN/ISP, datacenter/proxy detection). The resource is unique among siblings (resolve_dns, check_ports, list_proxies), so an agent can differentiate it without opening any schema.

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?

Gives two concrete use cases: verifying which IP/country traffic exits from, and confirming a VPN/proxy is active. There is no explicit when-not or named alternative, but the sibling set is disjoint enough that the intent is unambiguous.

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