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

Annotations already declare readOnlyHint=true, idempotentHint=true, and openWorldHint=false, so the safety profile is covered without the description. The description adds content-level transparency (what the report aggregates) but says nothing about freshness, caching, or how 'spike causes that recur' is determined. A 3 fits given annotations carry the behavioral load.

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 that leads with the purpose and then lists the three content groups. No filler, though the trailing clause 'spike causes that recur' is slightly cryptic and could be sharper.

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 it does enumerate the three report sections. Annotations cover safety and both parameters are documented in the schema. The only gap is that the boundaries against overlapping aggregate siblings remain 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 100% and both parameters document their format and defaults ('24h'/'7d'/'30d' max 90d; domain defaulting to the sign-in site). The description adds no parameter detail, so the baseline 3 applies.

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 resource precisely and enumerates its contents: channels ranked by conversions with growth and conversion rate, growing pages, and recurring spike causes. An agent can tell it produces a synthesized 'what's working' report. It does not, however, differentiate itself from overlapping siblings like get_overview, get_growth_actions, or find_traffic_spikes.

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 phrase 'Evidence for marketing planning' implies the use case, giving implied rather than explicit guidance. There is no statement of when to prefer this over get_overview or get_growth_actions, and no exclusions or prerequisites. Adequate but leaves routing to inference.

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