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

With no annotations, the description carries the full burden of behavioral disclosure. It only mentions splitting hostnames, yet the tool accepts nine heterogeneous parameters (ref, url, city, feed, host, json, path, zone, query) with descriptions indicating they are 'discarded after the shape check.' The description does not explain how these parameters are used, whether the tool is read-only, or what the output format is. This is a significant transparency gap.

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 fluff. It is concise and easy to read, but it omits essential details about the tool's broader functionality. The conciseness is good, but it comes at the cost of completeness.

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 complexity (9 parameters, no output schema, no annotations), the description is far too sparse. It does not explain what the tool returns, how the parameters are used, or when to call it. The mismatch between the description's narrow focus on hostnames and the wide range of accepted inputs leaves the agent uncertain about correct usage.

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 has its own description, meeting the baseline of 3. However, the tool description adds no context about how the parameters relate to the stated purpose (e.g., why a city or json would be relevant to a domain-shape tool). The schema descriptions themselves are clear but the tool-level description fails to reconcile them.

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) and resource (hostname into labels), and explicitly notes it does not include WHOIS or ownership data, which helps differentiate from other shape tools. However, it does not name sibling tools or clarify the relationship to other shape tools like github-repo-shape, so it's clear but not fully distinguishing.

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 implies a use case (splitting hostnames) but provides no explicit guidance on when to prefer this tool over alternatives, nor any exclusions or prerequisites. The 'without WHOIS or ownership data' hint suggests a contrast, but it doesn't mention other tools that might also handle hostnames (e.g., normalize-url).

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