List Countries

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

Annotations already indicate readOnlyHint=true and destructiveHint=false, so the baseline is 3. The description adds meaningful behavioral context beyond annotations by stating the output includes 'the number of tickers from each' and that it lists 'all' countries, which implies no filtering or pagination. This extra detail justifies a 4.

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 description is a single, concise sentence that contains no filler words. It communicates the full purpose in an efficient manner.

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 simple, zero-parameter list tool with read-only annotations and no output schema, the description adequately specifies the return concept (countries with ticker counts). It does not need to explain return format or additional behavior, making it complete.

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 has no parameters (0 params), which gives a baseline of 4 per the rubric. The schema covers all parameters vacuously, and there is nothing additional to explain in the description.

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 clearly states the tool's function: 'List all countries with the number of tickers from each.' It uses a specific verb (List), specifies the resource (countries), and adds the metric (number of tickers), which distinguishes it from sibling tools like list_exchanges or list_sectors.

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 provides clear context that this tool is for listing all countries, each with a ticker count. While it does not explicitly mention alternatives or exclusions, the specificity of the resource makes its usage evident, deserving a 4 rather than a lower score.

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