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

Annotations already declare readOnlyHint and openWorldHint, and the description adds useful context: the 10-lookup count for SPF and that it reports cause+fix. But it does not disclose rate limits, timeouts, or whether checks run live, which matters for an open-world network tool.

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?

Two sentences, front-loaded with the audit scope, then the usage triggers, then the return shape. Every clause earns its place.

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 purpose, triggers, checked records and return values (verdict, findings, report link). Missing only latency/rate-limit expectations for a live network audit; no output schema exists, but the return shape is described.

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%, so both parameters are already documented. The description adds no syntax or format details beyond the schema, so 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 verb+resource (audit a mail domain) and enumerates exactly what's checked (MX, SPF, DKIM, DMARC, PTR/FCrDNS, SMTP STARTTLS, MTA-STS, TLS-RPT, BIMI). Clearly distinguishable from siblings like check_dns or check_tls, which cover a subset.

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?

Gives three concrete triggering situations (spam/bounces, after provider or DNS changes, before tightening DMARC). No explicit exclusions or named alternatives, so a 4 rather than 5.

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