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

No annotations are provided, so the description carries the full burden of disclosing behavior. It does clarify that no WHOIS or ownership data is involved, which is useful, but it doesn't state side effects, return behavior, error cases, or that most parameters are discarded. Given the schema descriptions mention discarded fields, the description itself adds only minimal behavioral context.

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 concise sentence with no filler. It front-loads the primary action and includes a useful scope qualifier. Its brevity is appropriate, though it sacrifices detail that other dimensions need.

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 schema is complex with seven parameters, several marked as discarded, and there is no output schema or annotation. The description only addresses hostname splitting and provides no guidance on how the other parameters relate, what the tool returns, or how it fits with sibling tools. This is incomplete for an agent to correctly select and invoke it.

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 high: every input parameter has a description, so the baseline is 3. The description adds no meaning beyond what the schema already provides and doesn't even name which parameter corresponds to the hostname it mentions. It adds no value beyond the schema's structured fields.

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 verb and resource: 'Split a hostname into labels.' It also distinguishes itself from WHOIS/ownership lookups, which helps separate it from data-enrichment tools. However, it doesn't explicitly contrast with sibling tools like github-repo-shape or figma-url-shape, so some differentiation is left to context.

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 use this tool versus alternatives. The description implies a hostname-parsing use case but never states conditions, exclusions, or sibling alternatives such as normalize-url or wiki-title-ok. With seven parameters and many sibling tools, the lack of usage direction is a significant gap.

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