list_popular_destinations

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

With no annotations provided, the description carries the full burden. It conveys the read-only nature of listing, states what output includes (destinations and starting price), and gives usage constraints. However, it stops short of disclosing details like result limits or exact return format, leaving a minor gap.

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 concise and well-structured. The first sentence states the action and includes a key detail (starting price); the second sentence provides decision logic with alternatives. No unnecessary words.

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 no parameters and no output schema, the description is remarkably complete. It explains what the tool does, when to use it, and how it relates to sibling tools, giving an AI agent enough context to invoke it correctly.

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 has zero parameters, so schema coverage is trivially 100%. Per guidelines, a baseline of 4 applies for 0-parameter tools. The description adds context about the tool's scope but no parameter-specific details are needed.

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 popular eSIM destinations with starting prices, using a specific verb ('List') and resource ('destinations'). It distinguishes itself from siblings by specifying when to use it versus alternatives like list_plans and plan_trip.

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?

Explicit guidance is provided: use only when the user hasn't named a destination and wants ideas. It directly names alternatives (list_plans for one country, plan_trip for several), giving clear when-to-use and when-not-to-use criteria.

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