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

With no annotations, the description must disclose behavior. It only mentions the absence of WHOIS/ownership data, implying no external lookup, but does not clarify other side effects (e.g., network usage, error handling, return format). This is a thin disclosure for a tool with 9 parameters.

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 states the core action and a key limitation in an efficient manner, earning its place.

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 tool has 9 optional parameters and no output schema, but the description only covers hostname splitting. It does not clarify the role of the other parameters, what the tool returns, or any error cases. An agent would struggle to know how to use this effectively beyond the simplest case.

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 each parameter is already defined in the schema. The tool description adds no extra meaning beyond the simple action, so the baseline of 3 applies. It does not explain why some parameters exist (e.g., city, query) or how they relate to the hostname splitting.

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'), a resource ('hostname'), and the outcome ('into labels'), and explicitly excludes WHOIS/ownership data, which distinguishes it from domain‐lookup siblings. This is precise and differentiates the tool's role even without naming alternatives.

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 description provides no explicit guidance on when to choose this tool over siblings. It only states a negative (no WHOIS/ownership) but does not name alternative tools or conditions (e.g., 'use for label extraction; use fetch-status for connectivity'). Context is minimal.

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