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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful context that the report's records are returned inline, but says nothing about whether records are paginated or truncated for large reports, nor about error behavior when the report is not yet processed.

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?

A single front-loaded sentence with zero filler. It is arguably too terse for a tool that returns a nested report body, but nothing in it is wasted.

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 two fully documented required params and rich annotations, an agent can invoke this correctly, and there is no output schema to explain. Still, the description omits the return shape (report metadata plus the records array) and any retrieval caveats, leaving a modest gap for a report-fetching tool.

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 both required parameters (domain 'id' and 'report_id') documented in the schema itself. The description adds nothing about the ID formats or the relationship between the two, 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?

Specific verb (retrieve) plus resource (one DMARC aggregate report) and it notes that the embedded records come back with it. The word 'aggregate' subtly distinguishes it from get-dmarc-forensic-report and from list-dmarc-reports, though no sibling is named outright.

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?

There is no explicit statement of when to use this versus list-dmarc-reports or get-dmarc-forensic-report, nor any prerequisite about where id/report_id come from. The only signal is the word 'one', which implies single-item retrieval rather than listing.

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