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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely new behavioral context: the result is anchored to the last completed month, it carries a comparison baseline (1-year average), and it burns one trial-quota unit — the latter is a cost constraint no annotation conveys.

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?

Three short sentences: the return payload first, then the code legend, then the quota cost. The most important information is front-loaded and no sentence is filler, though the code legend could be visually separated from the comparison clause for faster scanning.

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 does sketch the return shape (hour/weekday distributions plus 1-year delta) and the temporal scope, which is what an agent needs before calling. It stops short of stating granularity, units, or whether the delta is percentage or absolute.

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 coverage is 75% and the to/from/agent parameters are already documented in the schema, so the real gap is the bare `code` enum — the description closes it by mapping 1010/1020/3010/3020 to visit-hour, visit-weekday, order-hour and order-weekday. It adds nothing for the remaining parameters, which is acceptable since the schema handles them.

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 specific verb and resource: it returns hour-of-day (0-23) and weekday distributions plus the delta against a trailing 1-year average, scoped to the last completed month. That is clear enough to act on, but it never contrasts itself with the sibling get_distribution, which an agent may reasonably confuse with this.

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 four code values are enumerated with their meaning, which implies which code to pick for a visit-time vs order-weekday question, and the trial-quota cost gives a reason to be sparing. There is still no explicit when-to-use / when-not guidance and no routing to or away from get_distribution or get_ai_insights.

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