check_availability

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

Without annotations, the description carries the burden and does well: it discloses the return fields (status, owner, expiry), lists valid statuses, and states that ENS character rules are validated and .eth suffix is optional. It does not describe potential limitations like network specificity or rate limits, leaving some gaps.

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 two sentences with no filler, leading with the action and immediately providing output details and input flexibility. Every clause adds information.

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 simple single-parameter tool, the description conveys the core action, output content, and input normalization. It stops short of any explicit read-only statement or response structure detail, but given the availability of the schema and the straightforward nature, it is sufficiently complete.

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 covers 100% of the parameter with a clear description and examples, so the baseline is 3. The tool description adds meaningful context by mentioning that both bare labels and .eth-suffixed names are accepted and that character rules are validated, which enriches the schema's description.

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 function with a specific verb ('Check availability') and resource ('ENS names'), and distinguishes it from sibling tools like search_ens_names or get_name_details by focusing specifically on availability status and key ownership/expiry data.

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 the tool is for checking availability, but does not explicitly recommend when to use it over alternatives or mention prerequisites/exclusions. Since the purpose is clear but there is no direct competition or when-not-to-use guidance, it relies on implied usage.

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