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 genuine value by disclosing the shape of the payload (counts plus unique-person counts) and the caveat that names reflect received events, but it says nothing about result volume, pagination, or truncation.

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 short sentences with no filler, and the most important fact — what the rows contain — comes first. It is efficiently sized, though the second sentence ('Names reflect received events') is terse enough to be ambiguous rather than clarifying.

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 explaining returns and does partially meet it by describing name, count and unique-user count. However, it omits how results are ordered, whether counts are approximate, and how many names can come back, which matters for a cardinality-exploding list endpoint.

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 range, filters, environment and app are already fully documented, including the custom range syntax and the filters' 90-day cap. The description adds no parameter detail beyond the schema, which is the expected baseline 3.

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 concrete resource (event names) and spells out the returned fields — occurrence count and distinct people — so an agent knows exactly what the call produces. The verb 'list' is only implied by 'Every event name seen', and it does not explicitly separate itself from the sibling list_events, which reads similar enough to cause hesitation.

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?

It says the names come from 'the range' but gives no when-to-use framing, no prerequisites, and never mentions list_events or get_breakdown as alternatives for event data. An agent must infer from the tool name alone when this is the right choice over other event-listing tools.

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