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

Annotations only declare readOnlyHint=true, but the description adds substantial behavioral detail beyond that: the exact five-number summary fields returned, the type-7 quantile interpolation and 2-decimal rounding, the conditional `points` field (null at or above `points_max`), the ordering by median descending, and the explicit statement that no provider key or name is returned. This is rich, non-redundant context.

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?

The key action is front-loaded in the first sentence, and the remaining prose is dense but functional (definition, fields, quantile method, edge cases). It is longer than average, and the statistical minutiae could be trimmed, but each sentence carries information an agent would otherwise have to guess.

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 parameters and no output schema, the description carries the full burden of describing the return value, and it does so thoroughly — field-by-field, including the conditional `points` behavior and the suppression caveat. Nothing needed to call or interpret this tool 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?

The tool takes zero parameters, so there is nothing to document and the baseline of 4 applies. The description correctly focuses its effort on output semantics instead of inventing parameter guidance.

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 (get the provider roster-size spread per country) and immediately defines the unit of analysis ('a roster size is the number of participant IDs one provider serves in the country'). This distinguishes it from statistical siblings like get_access_point_roster_mix and listing siblings like get_country_providers without requiring the schema to be opened.

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?

Usage is implied rather than stated: the closing note that 'a summary of a country with few providers says little' and that the console suppresses countries with fewer than 8 gives a practical caution. However, it never explicitly says when to prefer this over get_access_point_roster_mix or get_country_providers, so the agent must infer the fit.

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