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

Annotations already declare readOnlyHint=true, openWorldHint=true and destructiveHint=false. The description adds real context beyond them: it explicitly states it does not publish records or change DNS, that lookups are public and possibly cached, and that provider-specific values may require user input. This goes meaningfully past the structured safety hints.

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 well front-loaded: capability statement first, then goal semantics, return types, caveats, and side-effect disclaimer. Four sentences with essentially no filler, though the run of caveats makes it slightly heavier than necessary.

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, the description still enumerates what is returned (typed SPF/DKIM/DMARC/MTA-STS/TLS-RPT proposals or provider setup instructions). Combined with the explicit no-publish disclaimer and caching note, an agent has everything needed to call it 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 description coverage is 100%, so the baseline is 3. The description still adds value the schema lacks: it states that 'baseline is the default' for the goal parameter, explains both goal modes are supported, and clarifies that providers are optional and inferred when omitted.

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 (propose/generate) and resource (email-authentication DNS records and policy files: SPF, DKIM, DMARC, MTA-STS, TLS-RPT) plus the inputs it consumes (DNS configuration, optional providers). This clearly distinguishes it from siblings like diagnose_domain or add_domain, which do not generate record proposals.

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 useful in-tool guidance on the goal choice ('baseline (monitoring) or enforce goals; baseline is the default') and notes when user input may be required for provider values. However, it never says when to use this tool versus alternatives such as diagnose_domain or add_domain, leaving sibling routing to inference.

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