list_states

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

With no annotations provided, the description carries the burden of behavioral disclosure. It usefully reveals that this is a GET call, that country is an optional path segment, and that results include station counts. However, it does not disclose timeout semantics, behavior when country is omitted, or any other request/response traits.

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 two short sentences with no filler. The primary purpose is front-loaded, and the country constraint is stated immediately afterward in an efficient, scannable way.

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, read-only list tool with an output schema, the description is largely sufficient: it states the resource, endpoint, country constraint, and optional path behavior. Minor gaps remain around timeout meaning and the exact result when country is absent, but these are low-risk given the schema defaults and output schema.

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 must compensate. It adds meaningful semantics for the country parameter, including exact directory name requirement and an example ('Australia'), and the path notation shows the parameter is optional. The timeout parameter, however, receives no additional explanation beyond the schema default.

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 opens with 'States/regions with station counts', which clearly identifies the tool's purpose and resource, and reinforces it with the endpoint path 'GET /json/states[/{country}]'. It is distinguishable from station-level search siblings, though it does not explicitly name which sibling it is not.

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 implies when to use this tool: when you need states or regions along with station counts. It provides a specific usage rule ('Country must be the exact directory name') but does not explicitly state when to prefer this over alternatives like find_stations_by_state or list_countries.

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