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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false, and a closed-world hint, so the safety profile is fully covered elsewhere. The description adds useful context about what is returned (aggregate totals, per-assistant split, landing pages) but says nothing about windowing behavior, pagination, or what happens with sparse data.

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 tight clause with no filler, and the key scoping information (AI-assistant referrals) is front-loaded. The only minor weakness is that it is a noun fragment without an explicit verb, but it remains unambiguous.

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 three optional parameters, no output schema, and complete annotation coverage, the description does the remaining work by describing the return content (totals, per-assistant, landing pages). An agent could call this correctly from the definition as written; only defaults/limits are left to the schema, which already covers them.

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 already carries a description with defaults and bounds (days 7-90 default 28, limit max 200). The description adds no parameter meaning beyond that, so the baseline of 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 a specific data resource ('Visits that came from AI assistants') and enumerates the providers it covers (ChatGPT, Perplexity, Gemini, Claude, Copilot), plus the shape of the result (totals, per assistant, landing pages). It is clearly not ga4_traffic or ga4_sources, though it never names those siblings to make the distinction explicit.

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 scope implicitly tells an agent when this applies (AI-assistant referral traffic), but there is no explicit when-to-use/when-not guidance and no pointer to ga4_sources or ga4_traffic as the alternative for general referral or traffic breakdowns. Usage must be inferred from the tool name and description.

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