get_plan_coverage

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

With no annotations, the description carries the burden. It discloses a key behavioral trait: local plans have null group_id and cover only their own country, implying the tool is for regional/global plans. The verb 'List' also implies a read-only operation. It doesn't detail error handling or output format, but for a simple listing tool this is adequate.

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?

Two sentences, front-loaded with the main purpose, and no extraneous information. Every word earns its place, making it highly efficient.

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 tool with a single parameter and no output schema, the description is complete: it states what it does, where the input comes from, and an important edge case (local plans). The return type (list of countries) is implied by the purpose statement, so no further detail is needed.

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 covers the parameter with 100% description coverage, but the tool description adds value by explaining where the group_id comes from (a plan returned by plan_trip or list_plans) and the null group_id caveat. This goes beyond the schema's basic field description.

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 states the tool lists countries covered by a plan, using a specific verb ('List') and resource ('every country a regional or global plan covers'). It distinguishes from sibling tools like list_plans (which lists plans) and search_destinations, making the purpose 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?

It explains where to obtain the group_id (from plan_trip or list_plans) and clarifies that local plans with null group_id are not applicable. This gives clear context for when to use the tool, though it doesn't explicitly mention alternatives or exclusions beyond the local plan case.

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