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

Annotations already declare readOnlyHint=true, destructiveHint=false, openWorldHint=false. The description adds genuine beyond-annotation context: a data freshness caveat that the most recent ~3 days may be incomplete, plus explicit scope boundaries. It does not mention auth/profile requirements or how the freshness diagnostics surface, which keeps it short of 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?

Three sentences, front-loaded with what is returned, then the freshness caveat, then the routing exclusions. No filler and every clause carries information an agent needs.

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 an output schema present, return shape needn't be described, and all 10 parameters are fully documented in the schema. The description supplies the two things structured fields cannot: the ~3-day data lag and the scope boundaries relative to sibling tools.

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 limits, offsets, sort columns, date ranges, filters and the two toggles are all already documented in the schema. The description names metric dimensions but adds no syntax, defaults, or constraint detail beyond what the schema provides; 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 (Returns) plus the exact resource (Sponsored Products performance by ad placement) and enumerates the placement values (Top of Search, Detail Page, Other, Off Amazon). It also names the sibling tools it is not (get_campaign_performance/get_keyword_performance/get_sales_and_traffic), so an agent can distinguish it without opening any 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?

Explicit use case is given ('Use to compare placement-level spend, sales, ACOS, ROAS, CTR, and CVR') alongside explicit exclusions (no campaign totals, keyword performance, or organic traffic) and three named alternatives that cover those gaps. This is a textbook when/when-not/alternative routing statement.

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