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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so safety is covered. The description adds useful behavior in 'Cursor-paged' and the activity-type enumeration, but says nothing about ordering, empty results, or what happens for an unknown email.

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 sentences, zero padding, with the core capability front-loaded and the pagination note trailing as a secondary attribute.

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 return-value burden and does so by naming the event types returned plus pagination behavior. Only the shape/ordering of individual activity records is left unstated.

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 only 50%, and the description compensates: 'by email address' identifies the required key and 'optionally limited to one list' gives list_uid its meaning, while limit and cursor are documented in the schema itself. Only the exact semantics of the list filter (origin list vs. membership) remains slightly vague.

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?

Specific verb+resource: activity events (sends, opens, clicks, bounces) for exactly one subscriber identified by email. The enumerated event types clearly separate it from profile-oriented siblings like mailblaze_get_subscriber, though 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?

'Optionally limited to one list' implies the narrowing use case, but there is no explicit guidance on when to prefer this over get_subscriber or find_subscriber_by_email, nor when not to use it. Usage is inferable rather than stated.

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