region_find_regions_with_plan

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

With no annotations, the description carries the full burden of behavioral disclosure. The verb 'Find' and the 'Returns' section imply a read-only lookup, but the description does not explicitly state non-mutation, behavior for unknown plans, or potential edge cases such as empty results.

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, front-loaded with the core behavior, and uses a clean Args/Returns structure. Every sentence contributes useful information and there is no filler or redundancy.

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 one-parameter read-only lookup, the description is largely complete: the parameter is explained, the return is summarized, and an output schema exists to provide structural details. The main missing piece is differentiation from the many related plan/region sibling tools.

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 coverage is 0%, so the description must add meaning to the bare plan_id string. It does this by explaining that plan_id is 'The plan ID to search for' and by giving a concrete example, 'vc2-1c-1gb'. This is genuinely helpful, though it could go further by explaining how to discover valid plan IDs.

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 uses a specific verb, 'Find', a clear resource, 'regions', and a specific selection criterion, 'where a specific plan is available.' It distinguishes itself from generic region listing, though it does not explicitly reference nearby sibling tools like region_get_availability or plan_get_plans_by_region_availability.

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 intended use is implied: call this when you know a plan_id and need all regions where that plan is offered. However, there is no explicit when-to-use/when-not-to-use guidance and no mention of alternatives, so an agent could still be uncertain about choosing this over the inverse plan/region availability tools.

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