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

The description adds behavioral context beyond the readOnlyHint annotation by specifying that results are paginated, filterable by type, and limited to sent campaigns. It does not contradict the annotation and provides useful details for a read operation.

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?

The description is two concise sentences that front-load the core purpose, followed by pagination/filter details and the REST endpoint. Every word earns its place, with no redundancy.

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?

The description covers the essential aspects: what is listed, that it is paginated, the optional type filter, and the scope (sent campaigns). Although no output schema exists, the phrase 'aggregate performance' gives a useful hint about the contents. Minor gap: no explicit mention of the return structure, but adequate for a list tool.

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 input schema provides complete descriptions for all three parameters (type, count, offset), so with 100% schema coverage the baseline is 3. The description only mentions 'Paginated' and 'optional type filter', which adds minimal value beyond the schema.

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 clearly states 'List campaign reports' with a specific verb and resource, and the parenthetical 'aggregate performance for sent campaigns' clarifies exact scope. This distinguishes it from sibling tools like list_campaigns (which lists campaigns) and get_campaign_report (which retrieves a single report).

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 provides clear context that this is the tool to use when you need aggregate performance for sent campaigns, and notes pagination and optional type filtering. However, it does not explicitly name alternatives or exclusions, such as pointing to get_campaign_report for individual campaign details.

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