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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuine behavioral value beyond them by naming what the aggregated data actually contains (per-agent, per-namespace, per-day breakdowns), though it omits cost, freshness, or time-window behavior.

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 efficient sentence, front-loading the data source before the breakdown list. The trailing 'and where' is mildly vague filler but the whole thing is compact with no wasted sentences.

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 describing returns and does so reasonably via the breakdown list. What is missing is sibling differentiation from get_stats and any scoping/freshness note, which keeps it short of full completeness.

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?

The tool takes zero parameters, which is the baseline-4 case; the description correctly does not invent parameter talk. One caveat: with no parameters, the scope of the statistics (which tenant, what time range) is fixed by the server and is never stated.

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 clear resource — usage statistics from the tenant activity index — and enumerates the aggregation dimensions (total operations, by agent, by namespace, by day). An agent knows what it gets, but the description never distinguishes it from the sibling get_stats, which is the most likely confusion.

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 closing phrase 'useful for understanding which agents are most active and where' implies a usage context but gives no when/when-not guidance and no routing against get_stats, index_recent, or index_search. 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.