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

Annotations already establish the safe-read profile (readOnlyHint, idempotentHint, destructiveHint=false, openWorldHint), so the bar is low. The description adds the default 30-day window, which is genuinely useful behavioral context, but says nothing about result volume, pagination, or how status filtering affects output.

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?

A single front-loaded sentence with zero filler that puts the metric list and the default date window in one pass. It is efficient, though it sacrifices some explanatory depth for brevity.

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 correctly enumerate the returned metrics, which covers the return-value burden. But aggregation grain (per campaign row?), how the status filter interacts with results, and date-range boundaries remain unstated, leaving gaps for a 4-parameter analytics 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 description coverage is 25%: only the property parameter is documented (customer id from list_properties). The description partially compensates for the date parameters by stating the default range, but the status enum (ENABLED/PAUSED/ALL) is described only as a returned field, not as a filter, so callers get no help on that parameter.

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?

It names the entity (campaigns) and enumerates the exact metrics returned (cost, clicks, impressions, CTR, conversions, cost per conversion, ROAS, status), which is a clear resource definition rather than a tautology. However, it never differentiates itself from ad-, keyword-, or device-level siblings, so the agent must infer that this is the campaign grain.

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?

There is no statement of when to reach for this tool versus ads_ad_performance or ads_keyword_performance, and no exclusions or prerequisites. The only guidance is the implied default date range, which is not framed as usage advice.

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