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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds genuinely new interpretive context: the returned address is the user's own only for desktop clients, while hosted chat apps will see the provider's server address. That caveat prevents a common misinterpretation and is not derivable from structured fields. Minor gap: no note on caching or whether the address can vary between calls.

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 sentences, both front-loaded with the highest-value information (what is returned, then how to interpret it). No filler, no restating of the title or annotations.

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?

For a zero-parameter, read-only tool with no output schema, the description covers the essentials: the value returned, its classification, and its client-dependent interpretation. It does not describe the response shape (field names or format), which is left entirely implicit in the absence of an output schema.

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?

The tool takes no parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The description instead spends its words on the return value's meaning, which is the right use of the space.

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 IP address the request arrived from, plus whether it is IPv4 or IPv6. This implicitly distinguishes it from a general 'ip_lookup' by making clear it reports the caller's own connection, not an arbitrary queried address, though no sibling is named explicitly.

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 implied rather than stated: an agent can infer this is for finding its own egress address, and the desktop-vs-hosted note warns when the answer is not the user's own IP. There is no explicit when-to-use/when-not framing or named alternative such as ip_lookup for looking up a third-party address.

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