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

Annotations already declare readOnly/openWorld/idempotent/non-destructive, yet the description adds substantial behavior beyond them: one call observes one address family, results are not identity proof, Cloudflare Worker subrequest semantics differ, and no results are stored or logged. It also details what operational events record and exclude, which is genuinely useful context an agent cannot get from structured fields.

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 the core purpose and the key client-vs-device caveat before the supporting detail. The trailing block on operational events, automation run identifiers and the privacy-policy link is tangentially verbose for a zero-parameter IP lookup, but each sentence is coherent and non-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?

An output schema exists, so return-value explanation is unnecessary, and the annotations already carry the safety profile. The description fully covers the calling semantics, exclusions, and privacy/telemetry behavior an agent needs, with nothing material missing for a simple lookup tool.

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 reinforces that the tool takes an empty object and notes the single-family scope of a call, which is correct and consistent, though there are no parameters whose semantics could add value.

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: inspect the public IPv4/IPv6 address observed for the calling connection, and clarifies it takes an empty object and returns ip and family. The critical semantic distinction (MCP client exit address vs. the user's device address) is spelled out, so an agent can immediately tell this apart from the CIDR-math siblings.

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?

Explicit when-to-use (observing the connection's public address) plus clear exclusions: it does not discover private local addresses, addresses before a proxy, or both families at once. It also routes the agent to alternatives (web tool or a machine-local CLI) when the user needs their own device's address, and flags VPN/proxy effects on the observed path.

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