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

Annotations already declare read-only, idempotent, non-destructive, closed-world behavior, so the safety profile is covered. The description adds genuine behavioral context beyond that: every metric is compared against the previous window of equal length, and detailed mode expands the payload at token cost. Filter/timezone semantics are left entirely to 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?

Two tight sentences: the metric list comes first, then the detail-mode expansion and the 'most questions in one call' framing. No filler, and the most decision-relevant information is front-loaded.

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 return values, and it does so by enumerating the headline metrics and the extra detailed-mode dimensions. The seven-parameter surface (filters, period/from/to, timezone) is only covered by the fully documented schema, so the description is adequate but not self-sufficient.

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 baseline is 3. The description does enrich the 'detail' parameter by spelling out what 'detailed' actually returns (top 5 pages, sources, countries, devices), which goes beyond the schema's vague 'adds columns and splits', but it says nothing about period, filters, or timezone handling.

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 names the exact metrics returned (visits, pageviews, events, bounce rate, visit duration, pages per visit) and frames the tool as the headline summary, which implicitly separates it from the drill-down siblings like get_breakdown and get_timeseries. It also states that 'detailed' adds top-5 pages, sources, countries and devices, so an agent can tell what the tool covers without opening the schema.

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?

It gives a clear usage signal: this answers most 'how is the site doing' questions in one call, implying it is the default entry point rather than a drill-down tool. It also contrasts concise vs detailed on cost/coverage. It does not explicitly name alternatives (e.g., when to prefer get_breakdown or get_timeseries), so it stops short of full when/when-not guidance.

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