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

Annotations already cover the read-only, non-destructive profile, but the description adds genuinely new behavior: the return is raw XML served as an embedded application/xml resource, plus a non-obvious authorization rule that billing-only membership is insufficient. Missing detail on size limits or failure modes for very large reports.

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?

Three short sentences, front-loaded with what is returned before the access constraints. No filler or restatement of the title.

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?

No output schema exists, and the description does the needed work by describing the return payload format. Combined with the authorization caveat, an agent has enough to invoke correctly; only edge-case behavior (large reports, retention) is absent.

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 50%: reportId is documented in the schema as coming from get_dmarc_records, while organizationId has no schema description. The description partially compensates by constraining organizationId (report must belong to it, regular access required), 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 concrete verb and resource: 'Returns the original raw XML for the specified DMARC report as an embedded application/xml resource.' The emphasis on raw XML implicitly separates it from the aggregate/record listing at get_dmarc_records, though no sibling is named explicitly.

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?

Explains prerequisites ('must belong to the specified organization', 'requires regular access... billing-only membership is insufficient') but never states when to pick this over get_dmarc_records or other siblings. Usage is implied by the prerequisites rather than given as routing guidance.

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