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

With no annotations, the description carries the full burden of behavioral disclosure. It discloses one meaningful thing—that the tool does not provide WHOIS or ownership data—but it says nothing about network access, validation behavior, error handling, or what the returned labels look like.

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, front-loaded sentence with no filler. It is appropriately terse, though it is arguably too sparse to fully support the tool's nine-parameter schema.

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?

There is no output schema and no annotations, so the description alone must provide enough context. It does not explain the return format, which parameter to use, whether a URL or bare hostname is expected, or how invalid input is handled.

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 description coverage is 100%, so the baseline is 3. Each parameter has its own description including discard behavior, but the tool description adds no guidance about which of the nine optional parameters is relevant for domain-shape calls.

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 ('split') and resource ('a hostname'), and the phrase 'without WHOIS or ownership data' distinguishes it from sibling shape tools like github-repo-shape or jira-key-shape. However, the large, generic input schema introduces some ambiguity about what this tool actually operates on.

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 explicit guidance about when to use this tool versus alternatives, and no sibling is named. The phrase 'without WHOIS or ownership data' implies a boundary, but it does not tell an agent when to choose a different tool or what to pass.

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