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

Annotations already cover the safety profile (readOnlyHint true, destructiveHint false), yet the description adds substantial behavior the agent could not otherwise know: minimum thresholds of 10 characters, 3 installs and 3 addresses, rounding to the nearest 5, complementary suppression of derivable counts, deduplication ('each character counts once'), and explicit 'No names, ever' plus explicit reporting of missing data.

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 core measurement is front-loaded in the first sentence, followed by scope, suppression rules, window and default behavior in a logical order. It is dense and the suppression sentence is long, but nearly every clause carries decision-relevant information rather than filler.

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?

An output schema exists, so return values need not be explained, and the description still covers the parts an agent needs to call it correctly: optional filters, default window, empty-argument behavior, thresholds and rounding. The only loose thread is the unexplained 'level band' grouping dimension with no corresponding parameter.

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 the schema already documents race, class, window and faction and the baseline is 3. The description confirms sensible semantics — all filters are optional and combine into joint groupings — and restates the window default, but adds little syntax or format detail beyond the schema. Note a minor mismatch: 'level band' is presented as a grouping dimension although no level parameter exists.

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 states a specific computation: character counts grouped by race, class, race-and-class, and faction-and-level band, drawn from an opt-in census. That is far more precise than the title alone. It does not, however, name or contrast any sibling tool, so an agent gets no explicit routing help beyond the obvious domain 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?

Usage is implied rather than stated: 'With no arguments, the overview: most played class first' tells the agent what a bare call returns, and the window sentence explains the default scope. There is no when-to-use/when-not guidance and no named alternative among the many sibling tools for an agent deciding between census aggregates and entity lookups.

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