list_regions

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

With no annotations, the description carries the behavioral burden. It discloses the return format, partial-match filtering, and pagination constraints, but it does not mention error behavior, required authorization, or result ordering for a read operation without annotation coverage.

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 compact and well-structured: purpose first, then args, then return type. Every sentence adds value, and the parameter list is easy to scan without unnecessary fluff.

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 reference-data list tool with one required parameter and pagination, the description covers the essentials: what it lists, the key filtering behavior, pagination limits, and return format. It could add a pointer to list_countries for obtaining valid country_id values, but the tool is otherwise complete enough to invoke 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?

Schema description coverage is 0%, so the description fully compensates by explaining every parameter: country_id, partial-match name filtering, page starting at 1, and page_size max 1000. This is exactly the semantic information an agent needs beyond the raw schema.

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 a specific verb and resource: 'List regions/states for a country.' This clearly distinguishes the tool from sibling list tools like list_locations and list_countries, and the country_id parameter makes its scope unambiguous.

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 gives implied usage context: regions are needed when specifying location addresses. However, it does not explicitly state when to prefer this tool over alternatives or when not to use it, leaving some inference to the agent.

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