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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds useful behavioral context about the output format (lowercase code, 'gb' example) and clarifies that this tool is a reference lookup, not a prerequisite for other calls.

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 a single dense sentence that front-loads the core purpose, then explains the code format, gives a concrete example, and provides explicit usage guidance. Every clause earns its place without 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?

With zero parameters, a rich output schema, and comprehensive annotations, the description fully covers what an agent needs: what the tool returns, how to interpret it, when to call it, and when to skip it.

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 and schema description coverage is 100%, so the schema has nothing to document. The description compensates by explaining the purpose of the returned country_code and how it connects to other tools.

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 returns the countries GotCashback covers, with a specific output detail (lowercase ISO 3166-1 alpha-2 code). It is distinct from sibling tools like get_stores_by_country or get_cashback_rates_by_store_id, which serve different purposes.

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 explicitly says when to use this tool: only to confirm country support or determine the correct country_code. It also states when not to use it—before store, cashback, or gift card lookups—because those tools accept country_code directly and search all countries when omitted.

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