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

Annotations already cover read-only/idempotent/non-destructive, and the description adds real behavioral context: default trailing-28-day window, the shape of the response, the 90-day cap on activity, and the Free-tier billing_gate behavior with an instruction on how to react. That goes well beyond structured fields.

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 purpose and return shape, then parameter guidance, then the gating caveat. Every sentence carries information; no repetition of schema or annotation content.

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 supplies the return shape, defaults, and tier gating — enough to call correctly. Only `top_n` semantics are unaddressed.

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 only 17%, so the description must compensate — and it does for `range_days`, `since`/`until`, and `include_activity`, including the 90-day constraint. `top_n` (with its 1-50 bounds) is left undocumented, a minor gap.

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 ('Fetch pageview and unique-visitor analytics for a site') and enumerates the return contents (totals, daily timeseries, top paths, top referrers). No sibling tool covers analytics, and the scope is unambiguous.

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?

Gives clear selection logic between `range_days` and `since`+`until`, and names the trigger for `include_activity` ('how's my site doing?'). It lacks an explicit 'do not use this for X' exclusion, but the context is strong.

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