create_subdomain

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It fails to mention that creating a subdomain is an on-chain write transaction, does not disclose side effects (e.g., gas costs, ownership changes), and provides no information about the outcome or response. This is a significant gap for a mutation tool.

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, clear sentence with no wasted words, making it concise and front-loaded. However, it is minimally informative and could have included more guidance without significantly increasing length, so it does not earn a perfect score.

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?

This is a mutating tool with no annotations and no output schema. The description only states the basic action, omitting the transaction nature, prerequisites beyond ownership, parameter behavior, and what the agent can expect in return. This is incomplete for an agent to invoke the tool confidently.

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% (all five parameters are documented in the schema), so the baseline is 3. The description adds no additional parameter semantics beyond what the schema already provides, which is acceptable but not value-added.

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 'Create' and identifies the resource as 'a subdomain under an ENS name you own', which clearly differentiates it from sibling tools like register_ens_name, transfer_ens, or renew_ens. The ownership condition adds scope, making the purpose unmistakable.

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?

It implies the prerequisite that the caller must own the parent ENS name ('you own'), but it does not explicitly state when to use this tool versus alternatives like register_ens_name or set_ens_records, nor does it mention any exclusions. This is implied usage rather than explicit guidance.

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