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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so safety behavior is covered. The description adds no further behavioral context such as how reporters are grouped, whether results are paginated, or how date range affects output.

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?

It is a single, concise sentence with no wasted words. However, it is under-specified rather than effectively front-loaded, and it omits the most useful scoping detail (date range).

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?

The tool has three parameters including date range and sits among many similar DMARC list tools. The description does not explain how to use the date filters, how results differ from related tools, or what the agent should expect, leaving meaningful gaps despite the simple schema.

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 schema already explains id, from, and to. The description does not add any parameter meaning beyond the schema, which is acceptable but not helpful.

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 identifies the resource as DMARC reporters, but it is phrased as a noun phrase rather than a clear action and does not explicitly say it lists them. It gives a vague sense of output (organizations that sent reports) but does not distinguish this from nearby siblings such as list-dmarc-sources, list-dmarc-asns, or list-dmarc-countries.

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 guidance on when to use this tool versus the many other DMARC list tools. It also does not mention the available from/to date filtering, which is a key usage decision for this endpoint.

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