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

Annotations already establish the safety profile (readOnlyHint=true, idempotentHint=true, openWorldHint=false), so the description only needs to add context beyond that. It adds useful detail about which engines and derived metrics are returned, but says nothing about feature-gating behavior ('where enabled'), data freshness, or result size, which are the remaining behavioral unknowns.

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 dense sentence that front-loads the verb and resource before enumerating outputs, with no filler or repetition. It is long but each listed item conveys a distinct capability, so it earns most of its length.

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?

For a read-only retrieval tool with no output schema, the description does the important work of telling the agent what comes back (per-engine visibility, AI Overviews, PAA, gaps, cited competitors). What is missing is any mention that site_id is required and comes from list_sites, which the schema covers but the description could reinforce for correct invocation.

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%, so both parameters (site_id and weeks, with its default of 4 and max of 26) are already documented in the schema. The phrase 'per keyword' hints at aggregation granularity but adds no meaning about the parameters themselves, 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 a specific verb ('Show') and resource ('AI answer visibility per engine') and enumerates the concrete data surfaces it covers (AI Mode, ChatGPT, Claude, AI Overview, People Also Ask, answer gaps, cited competitors). No sibling tool overlaps this scope, so an agent can route to it without opening the schema.

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 use this tool versus alternatives such as get_site_metrics, get_competitors, or get_keywords, and no prerequisites or exclusions are given. The 'where enabled' fragment hints at feature-gating but never explains what it means for the caller.

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