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

With no annotations, the description carries the full burden. It discloses that it is DNS-only, stateless, returns null on DNS lookup failure, and is not signature verification. It also explains the pairwise nature and future build dependency, providing meaningful behavior beyond a simple check.

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 structured with clear sections for purpose, distinction, inputs, and returns. While longer than minimal, every part adds value, especially the return field explanations which are essential given no output schema. It could be slightly more concise but remains well-organized.

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?

With no output schema and minimal parameter schema, this description fully covers the tool's semantics: it lists all return fields, their possible values, meaning of null, and the underlying DNS behavior. It also explains the conceptual background (pairwise ads.cert) and limitations, making the description complete for effective use.

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 coverage is 0%, so the description compensates by stating the domain is a query parameter and required. It also implicitly defines the domain format by showing how it's used in the DNS lookup pattern (`_adscert.{domain}`), but lacks explicit format constraints like protocol or trailing dot.

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 the tool reports whether a domain publishes ads.cert DNS records, a specific readiness signal. It also explicitly distinguishes itself from signature verification and sibling tools by noting it is DNS-only and stateless.

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?

It gives clear context: this is for checking ads.cert readiness, not for verifying signed requests (which would require delegation). It also notes DNS-only and stateless, implying when this tool is appropriate, though it doesn't enumerate alternative tools.

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