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

Annotations already cover readOnly, openWorld and non-idempotent hints, but the description adds genuinely new operational context: credit cost per successful call, that repeated calls may charge again (consistent with idempotentHint=false), and that returned data should be treated as untrusted. It does not state rate limits or historical depth.

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?

Four short sentences, front-loaded with purpose, followed by cost, repeat-charge and trust warnings. Every sentence carries distinct operational information with no filler.

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 no output schema and full parameter coverage, the description is largely sufficient; the credit-cost and untrusted-data notes are valuable for an open-world paid API. It could say more about the historical range and update cadence of the returned estimates.

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%, including the ASIN pattern, marketplace enum and returnFields usage, so the schema does the heavy lifting. The description adds nothing about parameter behavior (e.g., how marketplace affects historical coverage), so 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?

States a specific verb and resource: 'Retrieve current and historical sales estimates for an ASIN.' An agent can distinguish it from amazon_sales_prediction_bsr only by inference from the 'ASIN' phrasing, since no sibling is named explicitly.

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?

No guidance on when to choose this over amazon_sales_prediction_bsr or amazon_asin_sales_trend, and no exclusions or prerequisites beyond a cost warning. The agent must infer selection criteria from tool names alone.

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