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

Annotations supply the safety profile (readOnly, non-destructive, closed world), and the description adds substantial behavior beyond them: data freshness relative to the ~72-hour Business Reports lag, exclusion of Non-Amazon/MCF channels and canceled orders, reconciliation with get_sales_summary, per-ASIN row grain with account totals, and how Pending FBA prices are enriched versus left as estimated_revenue. That is unusually rich disclosure for a read tool.

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-loads the critical scoping sentence before the mechanics, and most clauses carry actionable information. It is dense and jargon-heavy ('deterministic ASP-filled estimate'), with a couple of clauses that could be tightened, but there is little outright waste.

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 complex, lag-affected sales tool it covers exclusions, freshness, grain, limit semantics, enriched vs estimated revenue, and alternatives to sibling tools. An output schema exists, so return-shape explanation is optional, yet the mention of structuredContent.totals adds useful orientation rather than padding.

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 the baseline is 3, but the description adds real semantics not in the schema: 'Limit applies to ASIN rows only', which clarifies the grain the limit constrains. It does not elaborate on fulfillment_channel or include_raw_rows beyond the schema.

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 ('today/current-day Amazon marketplace sales from orders/order items') and immediately scopes it as current-day only. It names the siblings it is not (get_sales_summary, get_sales_velocity, get_sales_and_traffic, get_orders) so an agent can discriminate without opening another 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 when-to-use ('Use only for today/current-day'), explicit when-not ('Do not use for yesterday, historical dates, or ranges'), and it routes to named alternatives for each excluded case, plus a pointer to sales_completeness_state for current-day coverage.

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