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

No annotations are provided, so the description carries the full burden. It discloses that the tool splits hostnames and discards WHOIS/ownership data, but it says nothing about how the other 8 parameters behave (e.g., are they validated, discarded, or used?). The description gives no indication of side effects, permissions, or error handling, making behavior opaque for the broader input set.

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?

A single, tightly worded sentence with the core action and a key exclusion. It is front-loaded and contains no filler.

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 tool with 9 parameters, no output schema, and no annotations, the description is severely incomplete. It only explains one use case (hostname splitting) and leaves the purpose of the other parameters unexplained, nor does it mention return values or error behavior. An agent would not know how to correctly invoke this tool for inputs other than hostnames.

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?

Schema coverage is 100%, so all 9 parameters are already described individually. The description adds no extra meaning beyond the hostname example; it does not explain how parameters like 'city' or 'json' relate to the stated purpose. Given high schema coverage, a baseline of 3 is appropriate, but the description fails to compensate for any ambiguities.

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 hostname into labels) and explicitly excludes WHOIS/ownership data, which differentiates it from some siblings. However, the input schema includes 9 parameters (ref, url, city, feed, json, path, zone, query) that are unrelated to hostname splitting, so the description only covers a fraction of the tool's apparent scope, leaving agents uncertain about the full purpose.

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 like normalize-url, browser-url-ok, or figma-url-shape. The description does not mention conditions, exclusions, or comparisons to sibling tools, leaving the agent to guess.

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