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

Annotations only cover the safety profile (readOnly, non-destructive, closed-world). The description goes well beyond them: cumulative stats refreshed daily, a rolling two-year coupon window vs a rolling 90-day deal window, and the precise semantics of start/end dates (SP Promotions API schedule when a promotion exists, otherwise the report request window). It also states the output is factual only with no recommendations, which sets accurate expectations.

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?

Front-loaded with the two view modes before the date and freshness caveats, and every sentence carries information. It is long for a description, and the view= details partially restate the schema's view description near-verbatim, which is mild redundancy.

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 13 parameters, an output schema present, and annotations covering safety, this description supplies everything else an agent needs: view selection, filter scope per view, date-bound semantics, refresh cadence, coverage windows, and the Brand Tailored Promotions blind spot. Return values are correctly left to the output schema.

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 parameters are already documented and the baseline is 3. The description adds real meaning for the hardest parameters: what start_date/end_date actually bound (promotion start datetime) and which clock they follow, plus the default windows for each view. It does not add much for id/asin/status beyond what the schema says.

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 names a specific verb and resource ('Returns Amazon promotion performance') and then splits the resource into two clearly delineated surfaces (view=coupon vs view=deal), naming the exact upstream reports (GET_COUPON_PERFORMANCE_REPORT, GET_PROMOTION_PERFORMANCE_REPORT). An agent can distinguish this from ad campaign tools without opening the 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?

It gives explicit context for choosing a view and states a hard exclusion ('Brand Tailored Promotions have no API and never appear here'), which is useful when-to-avoid guidance. However, it never names a sibling alternative (e.g., get_campaign_performance or get_search_query_performance) for non-promotion performance questions, so routing against other tools is left to inference.

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