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

Adds substantial behavior beyond the readOnlyHint annotations: no sampling, and incomplete or stale data raise an error rather than producing false negatives (an explicit anti-false-negative guarantee). The prerequisites (synced data-hub, linked Ads) tell the agent when the call will fail. This is genuinely useful context an agent can act on.

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?

Opens with the READ-ONLY guarantee and follows with output scope, behavior, parameter guidance and prerequisites in a logical order. Dense with parenthetical clauses but every sentence carries information; 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?

For a five-parameter tool with no output schema, the description covers the returned fields (SKU, title, stock, sales, coverage), the failure mode, and prerequisites. The gap is the undocumented lookback_days and only_in_stock parameters, but overall an agent has enough to call it correctly.

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 only 40%, so the description must compensate. It does explain the only_with_sales + only_uncovered interaction, but lookback_days and only_in_stock are undocumented in both schema and description, leaving half the parameters ambiguous. Partial compensation only.

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: enumerating every ASIN in an outpost's catalog and recent sales with SKU, title, stock, sales and live Sponsored Products coverage. The scope (coverage audit, one row per ASIN, cross-referencing Product Ads and campaign/group state) differentiates it from siblings like ads_list_sp_product_ads, though it never names an alternative directly.

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?

Gives explicit conditional guidance: use only_with_sales=true combined with only_uncovered=true for sold products lacking active SP, and lists prerequisites (synced data-hub, connected Ads). It stops short of naming a sibling alternative or stating when NOT to use this tool.

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