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

With no annotations provided, the description carries the full burden. It adds only a minimal behavioral note ('without WHOIS or ownership data') but omits any side effects (e.g., discarding inputs) or output characteristics. It does not contradict annotations because there are none, but it is far from transparent.

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 sentence, but it is under-specified rather than appropriately concise. It fails to convey essential information about the tool's scope and usage, making it inefficient for an agent.

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 tool with 9 parameters, no required fields, and no output schema, the description is severely incomplete. It does not explain the purpose of most parameters, what the tool returns, or when to use it, leaving agents unable to call it correctly.

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 describes all 9 parameters (coverage 100%), so the baseline is 3. The description adds no extra meaning beyond the schema—it only aligns with the 'host' parameter and ignores the others, providing no additional semantic value.

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') but the input schema exposes 9 unrelated parameters (url, city, feed, json, path, zone, query). This mismatch makes the actual scope unclear—it appears to be a generic shape-checker, not just hostname splitting. It also does not differentiate from sibling shape tools like github-repo-shape or jira-key-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?

There is no guidance on when to use this tool versus alternatives. The single sentence offers no context, no exclusions, and no mention of conditions that select this tool over its many shape-checking siblings.

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