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

With readOnlyHint/idempotentHint already covering the safety profile, the description goes well beyond structured fields: it flags that `messages` is permanently 0 (a dead metric, not a feature), that `bookings`=0 is a genuine gap, and that location strings are auto-matched. That is exactly the kind of context that prevents a wrong user-facing conclusion.

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 what the tool measures, then constraints. It is dense but every clause carries information (metric list, window cap, dead-metric warning, location formats). The messages/bookings digression is long but earns its place by preventing misuse.

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?

An output schema exists so return values need no explanation. For a 2-parameter read-only insights tool, the description covers scope, metric meanings, window bounds, and location resolution — nothing an agent needs to call it correctly is missing.

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 0%, so the description must carry the semantics, and it does: `days` is documented with default 30 and max 540 (the ceiling is absent from the schema), and `location` accepts either a gbp_list_locations value or a business name/domain with auto-matching.

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: 'Google Business Profile PERFORMANCE insights' and enumerates exactly which metrics (impressions, calls, directions, website clicks, bookings). This clearly separates it from gbp_location_details, gbp_reviews and gbp_list_posts, which do not return performance data.

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?

It implies when the tool applies (measuring how customers find and act on the listing) and gives real usage rules for interpreting output ('never advise the user to turn messaging on'). However, it never names an alternative sibling or states when NOT to reach for this versus e.g. gbp_location_details or a generic report tool, so routing guidance stays implicit.

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