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

Annotations already declare the safe-read profile (readOnlyHint=true, destructiveHint=false), and the description goes well beyond them: source precedence (Sales API vs Business Report vs order-item fallback), exclusion of Non-Amazon sales_channel values, how total_sales/estimated_total_sales/unpriced_unit_count are computed, that canceled orders contribute nothing, and that order_count stays null for Business Report rows. These are non-obvious data-lineage facts an agent could not infer from annotations or schema.

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?

Purpose is correctly front-loaded in the first sentence, but the remainder is one dense run-on paragraph of conditional lineage rules with no grouping or headings. Each clause carries real information, yet the wall-of-text structure makes it hard to scan for the actionable caveats (sales_channel_scope, unit_count_basis, is_final).

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?

An output schema exists, so return-value detail is not required, and the description still supplies the completeness/comparability guidance (sales_completeness_state, is_final, revision_state, timezone_basis, reconciliation to get_orders) needed to use those fields correctly. Given the tool's complexity, nothing critical to correct invocation is missing.

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 100%, so every parameter is already documented (including a detailed sort_by description matching the one in the prose). The description reiterates sort/estimate semantics but adds no filter syntax, format, or default behavior the schema lacks, so 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 opening line states a specific verb+resource+scope ('account-level daily Amazon marketplace sales totals') and pins the output grain ('one row per day with revenue, units, and orders'), which immediately separates it from ASIN/SKU or order-level siblings. An agent can identify what this returns 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 both when-to-use ('daily ... totals, including yesterday or date ranges') and explicit exclusions with named alternatives: 'Do not use for ASIN/SKU breakdowns, individual orders, or off-Amazon fulfillment volume; use get_todays_sales, get_sales_velocity/get_sales_and_traffic, get_orders, or fulfillment tools.' Routing is unambiguous.

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