dmarc_summary

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

Annotations already declare readOnlyHint=true, so the safe read-only nature is established. The description adds that it operates over stored aggregate reports and summarizes specific metrics, which is useful context, but it does not disclose output format, boundary behavior, or how the optional filters affect results.

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, compact sentence that front-loads the tool's purpose and then states the key fields in the summary. Every clause adds information and there is no filler.

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 read-only summary tool with three optional parameters and no output schema, the description gives a basic mental model: it produces a compliance summary with pass rate, top sources, and disposition totals. However, it does not describe the expected response structure, edge cases like empty results, or timezone/date-range behavior, leaving an agent to risk on assumptions.

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?

The input schema has 100% description coverage for all three parameters ('to', 'from', 'domain'), so the schema carries the burden. The description does not add meaning beyond the schema; it only implies date range and domain filtering by naming the report scope.

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 names a specific verb and resource ('DMARC compliance summary') and details the exact metrics covered (pass rate, top sending sources, disposition totals). No sibling tool is DMARC-specific, so it clearly stands out.

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 guidance on when to use this tool versus alternatives like get_stats or list_emails. The description implies a reporting use case but does not state exclusions, prerequisites, or when a different tool would be more appropriate.

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