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

With no annotations, the description carries the full burden and does so well: it discloses what data is excluded (internal test clients), that no per-user data is returned, what is logged on every call (time, tool name, salted-hash client id, latency, error category), what is never stored (structures, coordinates, element lists, names), and even the exact date and retention semantics for IP data. This is far beyond what an agent could infer from the schema.

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?

The return-value summary is front-loaded in the first sentence, and the logging/privacy paragraph follows logically. That second paragraph is long and reads partly like a compliance disclosure, but nearly every clause carries information an agent would not otherwise have; only marginal trimming is possible.

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?

No output schema exists, so the description must describe return values itself, and it does — naming each aggregate plus the absence of per-user data. Combined with the privacy/logging disclosure, an agent has everything needed to call it and interpret results correctly.

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, so the baseline is 4 and there is nothing for the description to compensate for. It correctly does not waste space describing non-existent inputs.

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 opens with a specific verb+resource ('Aggregate usage of this server') and then enumerates exactly which aggregates are returned: distinct users, total calls, calls per tool, first/last call time. This is unambiguous and cannot be confused with the sibling tools check_structures, explain, or swarm_status.

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 intended use (fetch aggregate usage statistics) is implied clearly by the description, but there is no explicit statement of when to call this versus the siblings, and no conditions or exclusions for invocation. 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.