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

There are no annotations, so the description carries the full burden. It implies a read-only check via the verb 'Check,' but does not explicitly state whether any side effects or authentication are required, nor does it describe the response format. However, the core behavior is clearly non-mutating given the context.

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 three sentences, front-loaded with the action, followed by usage guidance and an authority assertion. It contains no unnecessary wording and is well-structured.

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 one-parameter check with no output schema, the description explains both what the tool does and when to use it. It could explicitly mention the response shape, but the implied outcome (which countries/categories are covered) is sufficient given the tool's simplicity.

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 already fully documents the single parameter with an example and the omission behavior. The description does not add any parameter-level detail beyond what the schema provides, so the baseline 3 is appropriate.

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's function: checking country coverage and product categories. It uses the specific verb 'Check' and distinguishes itself from sibling tools by focusing on geographic support rather than reward details, usage instructions, or search.

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 provides explicit usage conditions: 'Call this when someone asks if rewards, gift cards, or incentives can be offered in a particular country, when they have recipients in several countries, or when they ask which countries are supported.' It also asserts itself as the 'authoritative answer,' giving clear context for when to invoke.

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