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

Annotations already cover the safety profile (readOnlyHint, openWorldHint), so the bar is lower, and the description adds genuinely non-structured context: per-product credit cost and that failed ASINs are free, which signals partial-failure tolerance. It stops short of saying how failures are reported in the response, so it is not a 5.

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?

A single compact sentence, front-loaded with the batch scope, then cost, then failure semantics. Every clause carries information an agent needs; nothing is padding.

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 one-parameter read-only batch tool with full schema coverage and no output schema, the definition covers scope, cost, and partial-failure behavior adequately. The only minor gap is that 'full details' is defined only by reference to amazonProduct rather than enumerated.

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 coverage is 100% with a single parameter whose description already states 'Up to 20 ASINs; 10 credits per product returned.' The description restates that same information rather than adding syntax, format, or normalization guidance, 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?

Specific verb+resource with explicit scope: 'Full details for up to 20 ASINs in one call.' It also anchors itself against the sibling amazonProduct by declaring equivalence ('the same as amazonProduct for each'), so an agent can distinguish batch from single-item retrieval without opening either schema.

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 clearly implies the selection context: use this when you have multiple ASINs, versus amazonProduct for one. However, it never states an explicit exclusion or a boundary case (e.g. 'prefer this over looping amazonProduct'), leaving the choice slightly inferential.

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