st_subdomains

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

With no annotations, the description bears full responsibility for behavioral disclosure. It only mentions that it returns FQDNs and requires an API key, but omits details about rate limits, pagination, idempotency, or error handling.

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 extremely concise with two short sentences, no redundancy, and front-loaded with the core action.

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?

Given the simplicity of the tool (1 param, no output schema), the description lacks completeness. It does not specify output format (e.g., list, array, delimited) or any constraints (e.g., maximum subdomains, rate limits).

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 only parameter 'domain' is fully described in the schema (100% coverage). The description adds no further semantic context beyond the schema, so baseline 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 clearly states it enumerates subdomains for a domain using SecurityTrails and returns FQDNs. The specific mention of 'SecurityTrails' helps differentiate it from sibling tools like crtsh_search or vt_subdomains.

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 notes the requirement for ST_API_KEY, which is a helpful prerequisite. However, it does not provide guidance on when to use this tool versus alternatives (e.g., when to prefer SecurityTrails over Certificate Transparency or VirusTotal).

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