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

Annotations already declare readOnly/idempotent/non-destructive, so the safety profile is covered; the description adds genuinely new behavioral context by stating results are "Counts only" rather than raw entries. The note that a day where the user restored the streak counts in `streakSavedDays` is a non-obvious domain rule that would otherwise cause miscounting. No return shape or performance/rate context, keeping it below 5.

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?

Two sentences, front-loaded with the payload enumeration, and every clause carries information (metric list, the 185-day cap, the streak-restoration rule, the counts-only qualifier). The first sentence is a dense comma list but is still scannable; nothing is padding.

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 correctly takes on the burden of describing return contents and does so thoroughly, including two edge-case semantics. The remaining gap is input semantics — date boundary inclusivity, timezone, and the behavior when the range exceeds 185 days (error vs truncation) are all unstated.

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 0% for the two date parameters — only a regex pattern is given — and the description never names `from`/`to` or explains whether bounds are inclusive, what timezone applies, or which calendar the days are grouped by. The only semantic contribution is the 185-day maximum span, which is useful but does not cover the ambiguity an agent faces when picking values.

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 verb+resource ("Returns statistics for a period") and then enumerates the specific metrics returned: totals, weekly trend, weekdays, time of day, categories, most skipped/kept, longest streak and break. That is far more specific than a restatement of the name. It does not, however, differentiate itself from the sibling `zarok_get_week_summary`.

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 "period of up to 185 days" constraint implies this is the long-range aggregate tool versus a week-scoped sibling, but that routing is left to inference. There is no explicit when-to-use, when-not-to-use, or named alternative, which is a real gap given `zarok_get_week_summary` exists.

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