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

With no annotations, the description must carry the full burden of behavioral disclosure. It only mentions that WHOIS/ownership data is not retrieved, but says nothing about side effects, return values, whether parameters are discarded, or any other behavioral traits. The schema descriptions hint at some discarding, but the main description does not disclose this, so an agent cannot predict the tool's full behavior.

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 description is a single sentence with no fluff, front-loading the core action and adding a brief scope limitation ('without WHOIS or ownership data'). It is appropriately concise, though the brevity comes at the cost of missing essential context.

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?

The tool has 9 parameters and no output schema, and the description covers only a narrow hostname-splitting action. It does not explain what the tool does with URLs, JSON, timezones, queries, or other inputs, nor what it returns. This is grossly incomplete for such a parameter-rich 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?

The schema provides 100% description coverage, so each parameter is documented. However, the description's focus on 'hostname' only aligns with the 'host' parameter, leaving the other eight parameters unexplained in the description. The description does not clarify why these parameters exist or how they relate to the stated purpose, creating a semantic mismatch that could confuse an agent.

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?

The description states a specific action (split a hostname into labels) and a resource (hostname), which is clear for that narrow case. However, it does not explain the tool's overall purpose given the input schema accepts 9 diverse parameters (ref, url, city, feed, json, path, zone, query) that have nothing to do with hostnames, making the tool's scope confusing and failing to differentiate from siblings like figma-url-shape or github-repo-shape.

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?

No guidance is given on when to use this tool versus alternatives. There is no mention of conditions like 'use when you have a hostname to split' or exclusions such as 'do not use for WHOIS lookups'. The description leaves the agent to infer usage entirely.

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