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

Annotations already indicate a safe read-only operation (readOnlyHint=true, idempotentHint=true). The description adds interpretive context about the index scale (world average = 100, higher = more expensive), which is useful beyond annotations. However, it doesn't disclose the exact return format or any edge-case behavior, so a moderate score is appropriate.

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 one concise sentence that front-loads the action and immediately provides the interpretation scale. Every phrase is purposeful, achieving high clarity with minimal 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?

There is no output schema, so the description should explain what the tool returns. It explains how to interpret the index but does not explicitly state whether the output is a single number, both indices, or a difference. For a simple comparison tool, this ambiguity leaves a gap, so completeness is moderate.

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 provides full descriptions for both parameters (from and to as ISO alpha-2 codes), so the description doesn't need to add much. The description mentions 'between two countries' which loosely maps to the parameters but adds no additional semantic detail beyond the schema. With 100% schema coverage, baseline 3 applies.

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 compares food price index between two countries, using a specific verb and resource. It also explains the index scale and meaning, distinguishing it from sibling tools like compare_fuel_prices. This is a specific and clear purpose.

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 the tool is for comparing food prices between countries, but it does not provide explicit 'when to use' guidance or exclusions relative to alternatives such as compare_fuel_prices. While the context is apparent from the description, there's no explicit alternative naming or conditions, so it falls at the implied usage level.

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