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

Annotations only declare readOnlyHint=true, but the description adds substantial behavioral disclosure: data is cached for a day, small numerators are suppressed with nulls, denominators never suppressed, and region/sector codes are included for geometry joins. This goes far beyond the annotation and provides critical edge-case behavior that an agent must know.

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?

Although long, every sentence and clause contributes unique information. The opening sentence is a clear summary, followed by precise details on output structure, codes, suppression, and caching. There is no fluff, and the density is appropriate for the complexity of the returned object.

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 full burden of explaining return values. It thoroughly covers all output components (headline, cuts, cross-tabs, trend), data semantics (codes, suppression rules), and operational behavior (caching). This is complete enough for an agent to invoke the tool and interpret results correctly.

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?

The only parameter, country, is fully documented in the schema with an enum and description. The tool description does not add extra parameter semantics beyond what the schema already provides. Since schema coverage is 100%, 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 opens with 'Get a country's adoption aggregates' — a specific verb with a clear resource and scope. It then details the exact contents (headline totals, cuts, cross-tabs, trend) and even distinguishes from sibling tools by its country-level focus. This fully clarifies what the tool does and sets it apart from similar get_* tools.

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 description gives clear context about what data is returned and the country scope, so an agent can infer when to use it. However, it does not explicitly mention when not to use it or point to alternatives among the sibling tools (e.g., get_country_churn). It meets the 'clear context, no exclusions' level, but stops short of explicit alternative guidance.

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