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

The description goes well beyond annotations by disclosing non-idempotency, rate-limit consumption, 20-60s duration, and the 3-scans-per-IP-per-24h limit. It also explains the authority attestation requirement. These are important behavioral traits not inferable from the schema or annotations alone.

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 information-dense and front-loaded with a clear summary, followed by useful constraints and parameter details. It loses a point for minor redundancy: the 20-60s duration and rate limit are stated twice, once in the overview and again in the authority parameter explanation.

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?

Despite having no output schema, the description states what is returned (rating plus per-check detail), covers timing, rate limits, ownership requirements, and prohibitions. For a two-parameter tool, this is complete enough for an agent to invoke it correctly and avoid policy violations.

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 0%, but the description fully compensates: domain is defined with an example, and authority is defined as a mandatory attestation of ownership/control with explicit prohibition of third-party scanning. Both required parameters are given meaningful semantics beyond their names and types.

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 runs a one-time external-perimeter scan on a domain the user controls, listing specific checks (TLS expiry, domain renewal, dangling CNAME, CT-log lookalikes) and the output (rating plus per-check detail). This distinguishes it from sibling tools like pw_health or pw_stats by emphasizing the snapshot-like, domain-perimeter nature of the scan.

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 context: use it on a domain you control, and authority must be true. It explicitly prohibits scanning third-party domains. However, it does not directly compare against sibling tools or state when an alternative would be more appropriate, so it stops short of full alternative-exclusion guidance.

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