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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so the safety profile is covered. The description adds useful behavioral context: the window is bounded by days and system-generated events are filtered out. It does not say whether results are ordered, aggregated, or scoped to all users versus a segment, and no output schema exists to fill that gap.

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?

One front-loaded sentence with no filler; the parenthetical earns its place by clarifying what 'features' means. The 'excluding system events' clause is appended where it might read better as a separate qualifier, but nothing is wasted.

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?

This is a simple two-parameter read tool with annotations covering safety, so the description needn't be long. However, with 0% schema coverage and no output schema, the meaning of limit and the shape of the returned ranking are left entirely unexplained, which is a real gap for an agent composing a call.

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 0%, so the description carries the full burden for two parameters. It implies the days window ('over the last N days') but says nothing about the limit parameter or the maximum of 50, nor about the default of 10. Half the parameter intent is left undocumented.

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 resource (most frequent events) with a clear scope (last N days, system events excluded) and glosses it as 'what people actually do in the app.' It is more precise than the title alone. It stops short of explicitly distinguishing itself from analytics siblings such as query_events or list_event_names, so the agent must infer the difference.

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?

There is no explicit when-to-use guidance and no named alternative. An agent choosing between this, query_events, list_event_names, and get_active_users gets only an implied 'use this for a ranked feature summary' signal. The exclusion of system events is a scoping rule, not usage guidance.

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