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's 'without changing records or spending credits' partly restates that but adds genuinely new context — that mail operations consume credits and this call does not — and it discloses the shape of the response (totals plus paginated campaign list), which matters since there is no output schema.

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 sentences, front-loaded with the core purpose and zero wasted prose. The opening 'Get mail analytics summary.' is a near-verbatim restatement of the title and could be dropped, but the remainder is dense and useful.

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 no output schema, the description usefully describes the return payload (account-wide totals: sent, delivered, failed, opens, unique openers, average open rate, plus paginated per-campaign engagement). Annotations cover the safety profile and the nested schema covers inputs, so an agent has enough to invoke it correctly; only the date-filter semantics go unmentioned in prose.

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 description says nothing about page, per_page, start_date, end_date, or launched_only. In practice the nested schema carries a description for each of the five properties (including that dates filter by campaign launch date and are inclusive), so the parameter semantics are not lost — but the description contributes no additional meaning beyond the nested object, which is especially relevant given the reported 0% top-level coverage.

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 gives a specific verb and resource ('Get account-wide mail analytics') and enumerates what is returned: aggregate totals plus a paginated list of campaigns with per-campaign engagement. The 'account-wide' qualifier implicitly separates it from per-campaign siblings like dealmachine_get_mail_campaigns_id_analytics, but 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?

There is no explicit statement of when to choose this over dealmachine_get_mail_analytics_timeseries, dealmachine_get_mail_campaigns, or the per-campaign analytics tools. The only steer is the phrase 'account-wide', which implies scope but leaves the agent to infer the routing decision.

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