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

Annotations already declare the tool as read-only and idempotent. The description adds behavioral context by specifying the accepted code formats (ISO2, ISO3, aggregates) and the list of metadata fields returned, which are not specified in annotations. This informs the agent about acceptable inputs and expected output content.

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 concise sentences with no filler. The first sentence states the action and outputs, the second clarifies input formats. Information is front-loaded and every word contributes.

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 single-parameter lookup tool with annotations covering safety and a full output schema, the description is complete. It specifies accepted inputs, lists the fields returned, and is consistent with the read-only nature. Nothing an agent needs to call it correctly is missing.

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 input schema description already fully documents the parameter, including accepted code types and a pointer to browse valid codes. The description repeats these code types without adding new information, providing no additional semantic value beyond the schema.

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 verb 'fetches' and the resource 'full metadata for a specific country or aggregate entity', listing the types of data returned (region, income level, capital, coordinates, lending type). This distinguishes it from sibling tools that handle time-series data or search operations.

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 description implies usage for fetching country metadata but does not explicitly contrast with alternatives like worldbank_get_data or worldbank_search_indicators. It mentions accepted code formats, but does not directly state when to use this tool versus others. The schema suggests using worldbank_list_countries to browse codes, but that is not in the description.

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