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

With no annotations, the description carries the full burden and discloses important behavior: it is DNS-first, performs an HTTP GET only for CNAME matches, and defines what 'vulnerable', 'dangling', and 'potential' mean. It does not cover authentication, rate limits, or side effects, but for a read-only security check it provides strong operational context.

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 dense sentence but front-loads the core purpose and follows with necessary technical distinctions. It is appropriately sized for the complexity of the check, though splitting the status definitions could improve readability.

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 absence of output schema and annotations, the description supplies the relevant methodology and return statuses. It is largely complete for tool selection and invocation, though an agent might still wonder about rate limits or input restrictions.

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 schema has 100% description coverage for the single 'domain' parameter, and the description reinforces the domain scope implicitly. It adds no format or syntax details beyond the schema, so the baseline 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 states a specific verb and resource: checking a domain's subdomains for dangling-CNAME takeover risk. It explains the mechanism (Certificate Transparency enumeration, CNAME delegation) and defines distinct outcome statuses, making it clearly distinguishable from siblings like cert_transparency or dns_lookup.

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 gives a clear context for use: assessing subdomain takeover risk via dangling CNAMEs. It does not explicitly name alternative tools or when not to use it, but the scenario is specific enough that an agent can infer when this tool is appropriate.

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