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

Goes well beyond the annotations by disclosing a rate limit (60 reads/IP/minute plus hosted MCP quota), that no auth is required, that attribution may reflect a NAT/VPN/proxy/hosted runner rather than the device, and that missing or stale attribution is surfaced explicitly. These are the exact operational caveats an agent needs before relying on the output.

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?

The purpose is front-loaded in the first clause and each subsequent sentence contributes distinct information (auth, rate limits, identification caveats, boundaries, data-quality note). It is slightly dense, but there is essentially no filler to cut.

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-argument, read-only tool with an output schema already covering return values, the description supplies everything else: rate limits, auth posture, interpretation caveats, and explicit boundaries. Nothing an agent needs in order to call and correctly interpret it 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?

With zero parameters the baseline is 4, and the description reinforces this by stating 'No signup, key or target argument,' removing any ambiguity about whether arguments are expected. Nothing further is needed given there are no parameters to document.

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: report the source IP as Autonet sees it, plus cached ASN/geo. It even carves out a boundary ('Does not probe inbound reachability'), which implicitly separates it from probe-style siblings. It stops short of naming a specific alternative tool, so sibling differentiation is inferential rather than explicit.

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?

It signals the call needs no signup, key, or target, and clarifies what it does not do (no probing, no egress disclosure), which implies when it is appropriate. However, it never states when to choose this tool over neighbors like probe_me_now or diagnose_http, so usage is implied rather than directed.

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