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

The annotations already declare read-only, idempotent, non-destructive, closed-world behavior, so the bar is lower. The description adds useful behavioral context: the return rate is specifically a same-window comparison against units sold, and the answer is delivered via a 'narrative'. It does not describe pagination or rate limits, so it is not fully rich.

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 scope and metrics, then quickly lists the selecting questions, then notes the key output field. Every sentence carries useful information and there is 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, the description must carry the return-value burden, and it does indicate the important contents (units returned vs sold, top products, reasons, comments) and points to the 'narrative' as the answer. It is nearly complete, though a bit more on the narrative's structure would make it fully self-sufficient.

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%, with both parameters documented in the schema itself (days range/default and marketplace inference). The description only restates the window and marketplace scope, adding no syntax or format detail beyond the schema, so the 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?

The description states a specific verb and resource ('Customer returns'), a clear scope ('one marketplace over a window'), and the exact measures it reports (same-window return rate, most returned products, reasons, comments). This clearly distinguishes it from siblings like get_traffic_and_conversion or get_profit_by_sku.

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 example questions that select this tool ('how many returns', 'why are customers returning', 'which product has the most returns'), which is strong contextual guidance. It does not name alternative tools or state when not to use it, so it falls short of a 5.

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