ecp_domains_add_subdomain

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

With zero annotations, the description carries full responsibility for behavioral disclosure, but 'Add' reveals only that this is a mutation. It does not state whether re-adding an existing subdomain fails or overwrites, what side effects occur (auto DNS, web config, TLS), or any error/reversibility details, so the agent is left guessing about consequences.

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?

Eleven words, action front-loaded, and no filler or repetition. To ensure score faithfulness, every word earns its place and the same meaning-points cannot be further compacted without losing the ownership constraint.

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 two-string-parameter tool with no output schema or annotations, the description covers the essential intent and the key precondition. However it leaves post-conditions unexplained (whether the subdomain is immediately served, needs DNS records, or needs a certificate) and provides no error/failure context, so the agent must probe to be confident.

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 0%, so the description must compensate; it does map both parameters by naming 'domain' as the owned parent and 'subdomain' as the child being created. But it omits the required subdomain format (e.g., bare label 'www' vs. full 'www.example.com') and the exact relationship the schema expects, so compensation is partial.

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 provides a specific verb 'add' and a clear resource: a subdomain of an already-owned domain. The phrase 'a domain this account already owns' meaningfully distinguishes it from siblings like ecp_domains_add_domain and ecp_domains_delete, though it never names those siblings explicitly.

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 ownership precondition is implied by 'a domain this account already owns,' suggesting the parent domain must exist first (via ecp_domains_add_domain). However, there is no explicit when/when-not guidance, no naming of alternatives, and no direction about whether to reach for ecp_dns_add_record instead when only a DNS name is needed.

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