bevigil_get_subdomains

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It states the data source (mobile app analysis), the return type (unique subdomains), and explicitly differentiates from traditional DNS enumeration. This is valuable context beyond the basic 'get subdomains' name, though it lacks details on edge cases or error behavior.

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 three sentences, tightly structured with the primary action first, then use case, and finally a clarifying note. Every sentence adds information without redundancy or fluff, making it highly efficient.

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 single-parameter tool with no output schema, the description provides sufficient context: it explains the data source, use cases, and unique result behavior. It does not explain output format in detail, but for a list-returning tool with minimal complexity, this is acceptable.

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%, and the parameter 'domain' is already well-documented with format examples and exclusions ('Do not include protocol or paths'). The main description does not add extra semantic value for parameters, so a 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 ('Discover') and resource ('subdomains associated with a domain'), clearly stating the tool's function. It also distinguishes from siblings by specifying 'as found across mobile applications indexed by BeVigil', differentiating it from traditional DNS-based tools like bevigil_get_hosts.

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 provides clear context for when to use the tool ('attack surface mapping and asset discovery') and includes an important limitation note ('Results come from mobile app analysis, not traditional DNS enumeration'). However, it does not explicitly name alternative tools or state when not to use it, so it falls short of a 5.

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