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

Annotations already declare readOnly=false, openWorld=true, idempotent, non-destructive. The description adds behavior not in the structured fields: it is a paid x402 call costing 0.05 USDC with an X-Bazaar-Key header auth requirement, and it points to a free sample report. Missing only return-shape/pagination detail.

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?

Front-loads the payment/auth tag then the purpose and check list in essentially one dense sentence plus a sample link. Nearly every element earns its place; the URL is useful but slightly adds bulk.

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?

For a composite 6-check tool with no output schema, the description covers scope, the checks run, and the payment/auth model needed to invoke it successfully. It does not describe response contents, but with no output schema that requirement is relaxed.

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 100% with a single optional dmarc_policy parameter, so the schema already documents it. The description adds no information about dmarc_policy (or the additionalProperties passthrough), which is acceptable at high coverage but leaves it at the baseline 3.

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 verb (audit) and resource (domain deliverability & trust) and enumerates the six concrete checks chained (SPF/DMARC lookup limits, BIMI, TLS cipher suite, robots.txt, sitemap.xml, webhook HMAC). This level of detail lets an agent distinguish it from the many sibling suite_* tools without opening the schema.

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 enumerated checks imply the scenario (need email/domain trust posture), but there is no explicit when-to-use, when-not, or named alternative among the sibling suites. The agent must infer routing from the check list rather than from stated guidance.

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