get_sub_regions

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It only restates the function without elaborating on the nature of the returned data, potential ambiguity about whether sub-regions are immediate children or all descendants, or any edge cases. This adds little beyond the tool name.

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, front-loaded sentence that includes examples. Every word contributes to understanding the tool's purpose, with no redundancy or filler.

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?

The tool is relatively simple, but with no output schema and sparse annotations, the description should clarify the return value and the relationship between regionCode and regionType. The current description leaves ambiguity about whether it returns a list of child region objects or codes, and how the hierarchy works, making it incomplete for an agent to confidently invoke the tool.

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 schema covers 100% of parameters with descriptions and examples, so the baseline is 3. The tool description does not add significant semantic detail beyond the schema, making it adequate but not enhanced.

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 with a specific verb ('Get') and resource ('sub-regions of a parent region'), and provides concrete examples (states within a country, counties within a state). This effectively differentiates it from sibling tools like get_region_info, which likely returns details about a single region.

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 on when to use the tool, supported by examples that illustrate typical use cases. However, it does not explicitly mention alternatives or when not to use it, but the context is sufficient for an agent to infer the primary scenario.

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