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

The description discloses that the tool is a pure label-splitting operation and explicitly excludes WHOIS/ownership enrichment, which is useful behavioral context. However, with no annotations present, it stays silent on return format, error behavior, and side effects, leaving the agent to infer them.

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, front-loaded sentence with no filler; every phrase adds information. The core action and a key exclusion are communicated immediately.

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 7-parameter tool with no output schema and no annotations, the description doesn't specify which parameter is the hostname input, what the returned labels look like, or how it differs from sibling shape tools. The likely 'host' parameter is inferable from the schema, but the overall operational contract is incomplete.

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?

Input schema provides descriptions for all seven parameters (100% coverage), so the description adds little; only 'host' is arguably linked by the phrase 'hostname.' The description doesn't clarify how the other parameters relate to the split, but the schema already labels them as discarded.

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?

Description identifies a specific operation ('Split a hostname into labels') and a clear resource, and adds a scope exclusion ('without WHOIS or ownership data'). It doesn't name sibling tools, so differentiation is implicit rather than explicit.

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 explicit when-to-use or alternatives are provided; the only nod is the negative qualifier 'without WHOIS or ownership data,' which suggests a limitation rather than a routing condition. Among many sibling shape tools, an agent gets no reason to choose this over figma-url-shape or github-repo-shape.

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