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

Annotations already declare readOnlyHint, idempotentHint, non-destructive behavior and closed-world scope, so safety is covered. The description adds useful behavioral context by saying the result covers every sales channel, billing interval, regional rank and US price difference. It does not mention pagination or rate limits, but with rich annotations and an output schema that gap is minor.

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 front-loaded with the core operation, then uses two short example questions that earn their place by concretely illustrating the tool's use. There is no wasted text.

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?

Given the full input schema, rich annotations and the presence of an output schema, the description is complete enough for correct invocation. It communicates scope, return dimensions and intended question types without needing to repeat schema details.

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%, so the required region parameter and the product, locale and currency options are already well documented. The description reinforces that pricing is scoped to one product and one country/region, but adds no syntax or format details 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 states a specific verb and resource: show every plan price of one product in one country/region, broken down by sales channel and billing interval. It also names the extra returned context (rank and US difference), so an agent can distinguish it from sibling tools such as compare_prices or get_price_history.

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 example questions ('how much does ChatGPT cost in Japan?', 'is Claude cheaper in India than in the US?') clearly illustrate when this tool is appropriate. However, it does not explicitly name alternatives like compare_prices or compare_credits, nor does it state when not to use this tool.

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