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

With no annotations provided, the description must carry the full behavioral burden. It only states the core split operation and one negative constraint, but does not disclose return format, error handling for invalid hostnames, or any side effects. This is insufficient for a tool with no output schema.

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 zero fluff. It states the action immediately and the qualifier right after, making it easy to scan.

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 no output schema, so the description must explain what the tool returns, but it does not. It also omits practical details like which parameter to use (though the schema covers that) and what happens with malformed input. For an agent to call this confidently, more context is needed.

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 schema has 100% description coverage for all 9 parameters, so the description adds no extra semantic value. The 'host' parameter is clearly documented as 'Public hostname', which aligns with the description, but nothing beyond the schema is provided. Baseline 3 applies.

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 action ('Split a hostname into labels') and the resource (hostname), and adds a clarifying negative constraint ('without WHOIS or ownership data') that distinguishes it from enrichment tools. However, it does not name any sibling tools, so an agent may need to infer its place among the 'shape' 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?

No guidance is given on when to use this tool versus alternatives like github-repo-shape or normalize-url. There is no mention of prerequisites, context, or exclusions, leaving the agent to guess based on the name alone.

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