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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds that results are paginated, which is genuinely useful beyond the annotations, but it omits default/max page size behavior and any rate-limit context.

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?

Two compact sentences with zero filler; the core purpose is front-loaded and the pagination/filter note follows immediately. Every clause carries information.

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 read-only, three-parameter list endpoint with a fully documented schema and a readOnlyHint annotation, the description covers what an agent needs to invoke it. The only minor gap is the absence of guidance on choosing this over the singular report sibling.

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 the schema already documents type, count, and offset in full. The description's 'optional type filter' and 'paginated' merely restate what the schema provides, so the baseline 3 is appropriate.

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 (List) and resource (campaign reports), and the parenthetical 'aggregate performance for sent campaigns' disambiguates what a report actually is. It does not, however, explicitly distinguish itself from the singular sibling mailchimp_get_campaign_report or from mailchimp_list_campaigns.

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 notes pagination and an optional type filter, which implies usage for bulk retrieval, but never states when to choose this over mailchimp_get_campaign_report for a single campaign. No exclusions or prerequisites are given.

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