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

No annotations are present, so the description carries the transparency burden. It clearly indicates a pure syntactic operation with no WHOIS/ownership lookup, which strongly implies no external data fetch. It does not explicitly discuss output or side effects, but the behavior is unusually well scoped for a string-splitting tool.

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?

One clean, front-loaded sentence states the action and the key non-behavior. There is no wasted wording or duplicated schema content.

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 description and schema cover the core shape-check operation, but the nine optional parameters and the lack of an output schema leave room for ambiguity about what an agent actually needs to pass and what the result looks like. Complete enough for a trivial utility, but not fully self-contained.

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 schema already documents all 9 parameters. The description adds general hostname-label intent but does not clarify how the many optional non-host parameters relate to the operation; therefore the baseline of 3 is appropriate.

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 operation—'Split a hostname into labels'—and immediately clarifies the boundary with 'without WHOIS or ownership data.' This distinguishes it from lookup-style siblings and other shape tools such as github-repo-shape or figma-url-shape.

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?

The exclusion of WHOIS/ownership data gives an implicit usage boundary, but there is no explicit 'use this when…' or 'use X instead when…' guidance. An agent can infer intended use but must rely on sibling names to route correctly.

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