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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuine behaviour beyond that: aggregation over a time window, worst-first ranking, and one remediation action per finding. It stops short of describing pagination, counts, or what an empty result looks like, and there is no output schema to fill that gap.

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 tight sentences; the output shape and the ranking lead, followed by the data sources and the routing hint. The opening interrogative framing is slightly showy versus a direct verb, but it costs almost no length and no sentence is 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 one-optional-parameter read-only tool this is close to sufficient, and the description does convey ordering and per-finding remediation. With no output schema, the exact shape of a finding (fields, counts, whether healthy mailboxes appear) is still only loosely indicated.

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 100% and the single 'days' parameter is documented there, but the description adds real meaning: the window governs measured placement while the mailbox health check is the 'latest' snapshot, so the agent learns the parameter does not time-bound everything. That distinction is not visible in the schema alone.

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 outcome ('what is wrong with deliverability across the workspace'), the ordering ('worst first'), and the payload ('each with the action that fixes it'), then explains it fuses measured inbox placement with per-mailbox health checks. That composite framing distinguishes it from narrower siblings such as get_sender_reputation, get_blocklist_entry and get_inbox_placement_stats_by_date without needing to name them.

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?

Explicitly positions itself as 'the best first call when asked why are we landing in spam', giving a concrete triggering question. It does not state exclusions or name a drill-down alternative, but the 'combines' wording implies the narrower tools are for follow-up, so the routing is clear enough.

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