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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only describes a discovery method and does not mention data sources, rate limits, output behavior, or whether this is a read-only operation. An agent gets little insight into side effects or limitations.

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 short phrase with no filler. It front-loads the key concept (subdomain discovery via certificate transparency). The slight redundancy of starting with 'Subdomains:' (which mirrors the tool name) is minor and does not hurt clarity.

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?

Although the tool is simple and has an output schema to cover return values, the description omits the meaning of the 'q' parameter entirely. Without annotations, the agent cannot confidently know what to input. The description is not complete enough to guarantee correct invocation.

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 input schema has one parameter 'q' with 0% schema description coverage, and the description does not mention 'q' at all. The agent is left without any explanation of what value to pass (presumably a domain name). The description adds no semantic meaning beyond the bare parameter name.

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 method ('Certificate-transparency subdomain discovery') that identifies the tool's function. It clearly indicates subdomain discovery via CT logs, which distinguishes it from related sibling tools like subbrute, though it does not explicitly name alternatives.

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?

Usage is implied by the text: an agent can infer that this tool is for discovering subdomains from certificate transparency data when that method is preferred. However, there is no explicit guidance on when to choose this over subbrute, hostsearch, or other sibling tools, and no exclusions are noted.

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