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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is fully covered by structured data. The description's only behavioral addition is the filtering constraint that only places with providers are returned, which is genuinely useful scoping but not rich disclosure.

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?

A single front-loaded sentence with the scope qualifier attached to the noun phrase. Nothing redundant, nothing padded.

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 no-parameter, read-only enumeration tool with a full annotation set, the description supplies what an agent needs to select and call it. The only shortfall is that with no output schema, the return shape (e.g. grouping by country/region and how cities nest) is left implicit.

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 takes no parameters, so per the rubric the baseline is 4. There is nothing for the description to disambiguate, and it does not waste words describing nonexistent inputs.

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?

Clear verb ('List') plus the exact resources ('countries, regions and cities') and a scope qualifier ('that have sandbox providers'), so the agent knows precisely what comes back. It does not explicitly differentiate itself from siblings like list_categories or list_sources, but the resource domains are distinct enough that confusion is unlikely.

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?

Usage is only implied: the agent can infer this is the discovery/enumeration call for available sandbox locations, but the description never states when to use it, when not to, or how it relates to siblings such as list_sources. Acceptable for a simple zero-argument list tool, but there is an explicit gap.

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