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

Annotations already cover the safety profile (readOnly, idempotent, openWorld, non-destructive), so the bar is lower. The description adds genuinely useful behavior beyond them: the relative index scale and that a yearly history is returned, which tells the agent the response shape is a time series.

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 sentences, front-loaded with what the tool returns and immediately followed by when to call it. No filler, no repetition of the title, and the index baseline is placed where it is needed.

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?

An output schema exists, so return values need not be spelled out, and the description still sketches the payload (index plus yearly history). For a two-parameter read-only tool this is nearly complete; only the single-country vs comparison routing is left implicit.

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?

Schema description coverage is 100% and both parameters (country_code, locale) are fully documented in the schema, so the schema does the heavy lifting. The description adds only the scale interpretation, not any parameter-level guidance such as the locale's effect on output language.

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?

States a specific resource ('food price index for one country') and clarifies scope with the index scale (world average = 100). It implicitly separates itself from siblings like compare_food_prices and rank_food_prices via 'for one country', but never names or explicitly contrasts them.

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?

Gives a clear triggering condition: use when someone asks how expensive food, groceries or living is in a country. It stops short of stating when not to use it, e.g. routing multi-country comparisons to compare_food_prices or rank_food_prices.

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