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

Goes well beyond the readOnly/openWorld annotations: it discloses the truncated-answer marking with reason, the partial free index caveat, the 500 cap, dedup ordering, wildcard flagging, and public-only scope. The x402 payment model, price, accepted chains, and no-charge-on-failure are all stated.

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?

Dense but every sentence carries distinct information: output fields, ordering, fallback behavior, payment terms. Front-loaded with the resource and return shape, with operational caveats after.

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?

Covers output semantics, source fallback, truncation flags, pagination limits, and the payment requirement. With an output schema present, the description need not re-document return fields, yet it still summarizes them usefully. Complete for calling correctly.

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 100% and there is only one parameter, so the schema already documents 'domain' as a registered domain. The description adds no input syntax beyond what the schema provides; baseline 3 applies.

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?

States a specific resource (subdomains of a domain) and its source (certificate transparency logs), then enumerates the returned fields. It is clearly distinguishable from siblings like certs, ssl, and dns.

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?

Explains that CertSpotter is read first and crt.sh is the fallback, and clarifies results are deduplicated, newest-first, capped at 500. It doesn't explicitly say when to choose this over the sibling certs tool, but the source and output are clearly scoped.

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