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

With no annotations provided, the description carries full burden for behavioral transparency. It mentions 'best-effort eTLD', hinting at potential inaccuracies, but fails to disclose error handling (e.g., invalid input), return format, or whether the tool is idempotent.

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 concise with two sentences, front-loading the verb and resource. However, the second sentence restates the first partially, adding slight redundancy. Overall efficient.

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?

Given the tool's simplicity (one param, no output schema, no annotations), the description is incomplete. It does not specify the output structure (e.g., JSON fields), error behavior for invalid domains, or edge cases. An agent would need to infer expectations.

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?

The input schema has 0% description coverage, and the tool description does not clarify the expected format of the 'domain' parameter (e.g., whether to include scheme, port, or just the domain itself). The word 'domain' gives minimal meaning, but no examples or constraints are provided.

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 clearly states the tool parses a domain into components like labels, TLD, registrable domain, and subdomain. It distinguishes the tool from sibling url_parse which handles full URLs, though it does not explicitly differentiate from other domain-related tools.

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 a 'When' clause indicating the tool should be used to split a domain, but it lacks guidance on when not to use it or alternative tools (e.g., url_parse for full URLs). It implies the context but no exclusions.

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