List rotating-proxy regions

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

Annotations already indicate readOnlyHint=true, so the safety profile is clear. The description adds meaningful behavioral detail: without arguments it returns country codes/names, and with `country` it returns the state/city subtree. It also clarifies the distinction between `code` (for region) and `value` (for state/city), which is helpful for callers.

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 sentences, with the first sentence stating the core functionality and the second providing usage guidance. It is front-loaded, contains no fluff, and every sentence contributes value.

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 list tool with one optional parameter and no output schema, the description fully explains the behavior in both argument scenarios, the structure of output data, and how to apply the results in profile creation/update. This is complete for its complexity, and the presence of annotations further reduces the need for additional context.

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 already provides 100% coverage for the single `country` parameter, describing its type and effect. The description adds integration-oriented semantics by explaining how to use the returned fields in other tools, which goes beyond the schema's basic parameter description and enriches understanding of the parameter's role.

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 identifies the tool's purpose: returning proxy regions for rotating residential proxies. It specifies the exact output types (countries, states/cities) and how the optional `country` parameter changes the results, making it distinct from sibling tools like list_proxies.

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?

Explicitly explains when to use the tool: when configuring proxies in create_profile or quick_update_profile, and how to map the returned `code` and `value` fields to proxy.region, proxy.state, and proxy.city. This gives concrete, actionable usage context beyond just listing regions.

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