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

Annotations already declare readOnlyHint, destructiveHint=false, and openWorldHint=false, so safety is covered. The description still adds real value beyond that: window semantics (default 30, max 180), the fact that resumes_count is never windowed, and the reassurance that zero counts/averages are normal for new users.

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?

A single dense paragraph that front-loads the purpose and window semantics before listing returned metrics. The long enumeration of fields is somewhat run-on but every clause is informative.

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?

Although an output schema exists so return values need not be re-explained, the description's coverage of window semantics, the non-windowed resumes_count, and the zero-result caveat makes it self-sufficient for correct invocation. Nothing an agent needs to call it is missing.

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?

Reported schema coverage is 0%, so the description must carry the parameter meaning, and it does: period_days defaults to 30, is capped at 180, scopes the activity counts, and explicitly excludes resumes_count from windowing. It does not cover validation/error behavior for out-of-range values, keeping it short of a 5.

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 gives a specific verb+resource ('compact numeric summary of the user's activity') and enumerates exactly what is summarized, which implicitly separates it from event-listing siblings like get_recent_activity or get_usage. It never names an alternative sibling explicitly, so differentiation is inferred rather than stated.

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?

Usage context is implied (read aggregate activity over a look-back window) and the default/cap are given, but there is no explicit when-to-use versus when-not guidance and no pointer to alternatives such as get_recent_activity for event-level detail.

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