bevigil_get_subdomains

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

Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint=false. The description adds meaningful behavioral context beyond these: results are drawn from BeVigil's mobile app index rather than DNS, are unique subdomains, and reflect only what appears in that indexed dataset. This helps set expectations about coverage and source without contradicting the annotations.

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, front-loaded with the main purpose, and every sentence adds value: what the tool does, why it is useful, what it returns, and a caveat about data provenance. There is no filler or redundant restatement of the tool name.

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 tool is a simple read-only lookup with three well-documented parameters and informative annotations, the description is complete enough for an agent to select and invoke it correctly. It covers input domain, output type, data source, and practical use cases, and no output schema is needed to understand the list-of-subdomains return shape.

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%, with domain, limit, and offset all already documented. The tool description adds no parameter-specific semantics beyond the schema; it only restates the domain concept and output shape. Since the schema carries the full parameter burden, the 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') with a clear resource ('subdomains associated with a domain') and identifies the unique data source ('mobile applications indexed by BeVigil'). It also states the output ('list of unique subdomains'), which clearly differentiates it from sibling tools focused on hosts, URLs, S3 buckets, app packages, and wordlists.

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 usage context by naming attack surface mapping and asset discovery as intended use cases. It also includes an important scoping note that results come from mobile app analysis, not traditional DNS enumeration, which helps users judge relevance. It does not explicitly name sibling alternatives or exclusions, but the context is sufficiently clear.

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