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

With no annotations, the description carries the burden of behavioral disclosure. It scopes the data source and suggests a read-only aggregation operation. However, it does not disclose return format, pagination, or any limitations, leaving some uncertainty for an agent.

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 sentence with no redundant content. It front-loads the core action ('Listing totals') and scopes it efficiently. There is no wasted language or unnecessary detail.

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?

No output schema exists, so the description needs to convey the response structure. It specifies grouping by country and type but does not state the exact shape or whether the response is a list or mapping. For a zero-parameter tool, this is a moderate gap in completeness.

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 zero parameters, and the input schema is empty. The description adds context about the output dimensions (country and type), which is sufficient given the absence of parameters. This aligns with the baseline expectation for parameterless tools.

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 provides listing totals for the OTC marketplace, grouped by country and type. The specific country list and marketplace scope differentiate it from sibling tools like market_listings. However, 'Listing totals' is slightly ambiguous as a verb phrase, making it less crisp than it could be.

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?

No explicit guidance is given about when to choose this tool over siblings. The purpose statement implies it is for aggregated totals rather than raw listings, but no alternatives or exclusions are mentioned. There is no clear context about use cases or when not to use it.

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