checkRegisterAvailability

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

With no annotations, the description carries the transparency burden. It adds a meaningful behavioral trait by saying 'right now', indicating a live availability check, and it sets an upper bound of 200 domains. However, it does not disclose response format, error behavior, rate limits, or whether the check has side effects, so the burden is only partially met.

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 focused sentence with no filler, and the main action is front-loaded. The API reference link is directly useful without bloating the definition.

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 well-documented parameter, but no output schema exists and the description does not explain what the response contains. The API reference link helps, but an agent still lacks explicit information about the result format or per-domain availability details.

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 already fully documents the domains parameter, including comma-separated string/array and max 200. The description repeats the 200-domain limit but adds no new parameter semantics, so the baseline score of 3 is appropriate.

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 uses a specific verb ('Check') with a clear resource ('whether up to 200 domains can be registered') and a time qualifier ('right now'). It clearly serves a different purpose from sibling checkTransferAvailability and other domain 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 implies this is used before registering domains to verify current availability, but it does not explicitly state when to use it versus sibling tools or when not to use it. It gives useful context ('right now', up to 200 domains) but leaves the routing decision mostly to inference.

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