Get top countries by customer count

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

With no annotations, the description carries the full burden. It discloses the sorting order (descending by customer count, ascending by country for ties) and the default limit behavior. This goes beyond a simple 'returns top countries' and gives specific behavioral details.

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?

Two sentences, both essential. The first sentence states the ranking logic, the second explains the default and usage. No filler words; information is front-loaded.

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?

This is a simple tool with one optional parameter and no output schema. The description covers the ranking order, tie handling, default behavior, and a usage example. There is no missing information an agent needs to invoke it 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?

Although the schema has no descriptions (0% coverage), the description explains the 'limit' parameter explicitly: default to 1, higher limit yields a top-N leaderboard. This adds meaning beyond the schema's numeric constraints (min, max, default) and clarifies the parameter's role.

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 states the precise action: ranks countries by number of registered customers in descending order, with ties broken by country name. It also explicitly connects to a question ('which country has the most customers?'), distinguishing it from sibling tools that rank by spend or orders.

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 specifies the default behavior (returns single top country) and how to get a top-N leaderboard by passing a higher 'limit'. It gives a concrete use case ('Use this to answer...'). It does not explicitly mention alternatives or when not to use it, but the purpose is clear enough for an agent to select it appropriately.

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