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

No annotations are present, so the description carries the full burden of behavioral disclosure. It usefully states that WHOIS/ownership data is not included, but it does not disclose that inputs are discarded, that the operation is read-only, what it returns, or how invalid hostnames are handled. The schema notes some discarding behavior, but the description itself is thin.

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 single sentence is readable and front-loaded with the core action. However, for a tool with nine optional parameters and no annotations, this is under-specification rather than useful conciseness. There is no structure or grouping to help an agent understand the parameter space.

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?

Given nine parameters, no annotations, and no output schema, the description is incomplete. An agent cannot reliably know which parameter to pass, how the parameters interact, what the output looks like, or what edge cases exist. The detailed schema helps but does not compensate for the missing tool-level context.

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 each parameter already has a description and the baseline is 3. The tool description adds little parameter-level meaning beyond implying that 'hostname' maps to the host parameter; the other eight parameters are not explained at the tool level. The schema carries the semantic burden.

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 uses a specific verb ('Split') and resource ('hostname'), and adds the boundary 'without WHOIS or ownership data,' which clearly states what the tool does. However, it does not mention the many unrelated inputs in the schema (url, city, query, etc.) and does not explicitly differentiate from sibling shape tools, so it is clear but not fully contextualized.

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?

There is no guidance on when to prefer domain-shape over sibling tools such as url-shape, normalize-url, or fetch-status. The only usage hint is a negative one ('without WHOIS or ownership data'), which tells agents what not to expect but not when to call this tool. For a tool with nine parameters, this is insufficient.

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