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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered. The description adds real value beyond that: it discloses that outputs are aggregates only, that identities and individual answers are excluded, and that authentication is required.

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, each earning its place: what is returned, what is excluded, and the auth prerequisite. The core content is front-loaded in the first sentence.

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 carries the burden of describing return values and does so by enumerating the aggregate categories. It is nearly complete; only the behavior when wedding_id is omitted is unaddressed in the description (the schema hints at it).

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 there is only one optional parameter, whose conditional requirement ('required when the account has multiple weddings') is fully documented in the schema. The description adds nothing further about wedding_id, so the 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 specific verb and resource ('Returns aggregate wedding statistics') and enumerates the scope: guest totals by age band, RSVP counts, event counts, registry progress. The explicit exclusion of guest identities and individual event answers distinguishes it from list_my_guests and list_my_events without naming 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?

The description implies when it applies (a summary view rather than per-record listing) and states the prerequisite 'Requires sign-in', but never names an alternative tool or an explicit when-not-to-use condition. Usage is inferable but not spelled out.

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