Overview

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 behavior the annotations cannot: the partial-day comparison rule for ranges ending today, a hard 400-day range cap, timezone semantics, and a data-fidelity caveat that event/page/property text is reported exactly as visitors submitted it (a real signal about unvalidated content).

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?

Front-loaded with what the report returns, then comparison semantics, then input sourcing and constraints. Four compact sentences with no filler. The closing note on visitor-supplied text is slightly tangential but is a legitimate data-quality warning rather than 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 carries the burden of describing returns and does so at the metric level, plus it covers the range cap, timezone, and comparison window. It stops short of describing the response structure (field names, grouping, pagination), which is the main residual gap for a report tool.

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 100% and each parameter is documented, so the baseline is 3. The description goes further by supplying constraints absent from the schema — the 400-day maximum range length, the 'at most today' upper bound, and the project-time-zone interpretation of the dates — which meaningfully changes how an agent constructs the call.

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 concrete outputs (visits, identified users, conversions, failed writes, daily activity, top pages and events) and the period-over-period comparison, which is far beyond restating the title 'Overview'. It does not, however, name or distinguish itself from near-siblings such as visits, engagement or acquisition, so an agent still has to infer the boundary.

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 one concrete routing hint — the project id and the project's 'today' come from list_projects — which is genuinely useful for chaining calls. But there is no statement of when to choose this report over visits, engagement or acquisition, and no exclusions; usage is implied rather than prescribed.

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