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

No annotations, so the description carries the full burden; it does disclose the exact information returned and the important behavioral caveat that a remote agent sees the MCP server host's IP, not its own. It does not mention side effects, rate limits, or whether the lookup requires external network access, which a no-annotation read tool ideally would.

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, no filler, with the return-value summary and the caller-scoping caveat front-loaded in that order. Every clause 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?

There is no output schema, so the description appropriately enumerates the return fields, and the remote-agent caveat covers the one ambiguity that would otherwise cause misuse. Nothing needed to call 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?

The tool takes zero parameters, so there is no parameter semantics to explain; the baseline for a 0-param tool is 4. The description correctly implies no arguments are needed.

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?

Specific verb+resource ('Return the public IP address... of the caller') and enumerates the returned fields (ISP, ASN, location, timezone). This implicitly but clearly separates it from lookup_ip/batch_lookup_ip, which look up arbitrary addresses rather than the caller's own.

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?

"of the caller" establishes the condition that selects this tool over the sibling lookup_ip/whois_lookup tools, and the remote-agent note clarifies when the result may be surprising. It stops short of explicitly naming an alternative or stating when not to use it.

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