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 adds the useful precondition that the campaign must have been sent, but says nothing about pagination behavior, default page size, or what happens if the campaign was never sent or has no domain data.

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 front-loaded sentence with zero filler, which is efficient. Its brevity edges toward under-specification rather than verbosity, but there is no wasted wording to trim.

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 present, the description carries the burden of explaining what 'domain-level performance statistics' actually contains, and it does not enumerate metrics or the shape of results. For a paginated read-only report tool this leaves meaningful gaps around return content and paging defaults.

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 description coverage is 100%, so all three parameters (campaign_id, page, limit) are already documented in the schema, establishing a baseline of 3. The description adds no meaning beyond the schema, such as default page/limit values or maximum allowed limit.

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 ('Get domain-level performance statistics') and scopes it to a sent campaign plus a domain-level grain, which distinguishes it somewhat from campaign-wide reporting siblings. It stops short of naming an alternative or clarifying which metrics count as 'performance statistics'.

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 only usage signal is the implicit precondition 'for a sent campaign'. No guidance tells the agent when to reach for this over get_campaign_clicks, get_campaign_opens, analyze_campaign, or get_inbox_tracking, all of which are adjacent reporting tools in the sibling list.

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