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. The verb 'check' suggests a read-only operation, and the example clarifies the URL format. However, it does not disclose the return value format (e.g., boolean or other), nor does it mention any side effects, rate limits, or error behaviors. This is a moderate 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 sentence that front-loads the purpose and includes a useful example. Every element earns its place, with no unnecessary filler. It is well-structured for quick parsing.

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 is simple with one parameter and no output schema, so the description should ideally explain what the tool returns. While the example clarifies the input/output domain, the absence of an explicit return type or behavior description leaves the agent uncertain about how to interpret the response. For a simple check tool, this is a notable gap.

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 already fully describes the 'name' parameter with clear constraints. The description adds value by providing an example mapping ('my-site' → my-site.demo.st), which helps the agent understand how the input is used. This goes beyond the schema description, so a score above baseline is warranted.

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's purpose: to check if a subdomain is available on demo.st. The verb 'check' is specific, the resource is identified, and the example clarifies the output domain. It also distinguishes itself from sibling tools like reserve_subdomain and release_subdomain by focusing on availability.

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 usage contexts (e.g., before reserving a subdomain) but does not explicitly state when to use this tool versus alternatives. There is no mention of prerequisites or exclusions, so the guidance is implicit rather than explicit.

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