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

Annotations already declare readOnly/idempotent/non-destructive/closed-world, so the bar is low. The description adds genuinely new context: that the Ads connection may not exist, and the billing nuance that ad spend is billed separately from Amazon settlements and therefore excluded from profit figures. It does not discuss pagination or result limits, so not 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?

Two sentences, front-loaded with the capability and metric list, followed by the single most decision-relevant caveat (spend is not part of profit tools). No filler; every clause carries information.

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 compensates by enumerating the returned metrics and the connection-status field. Combined with 100% schema coverage on both params and full annotation coverage, an agent has everything needed to call and interpret it.

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% and the marketplace_id description is already very detailed (currency caveats, when to omit, call list_my_marketplaces first). The description only echoes the 'over a window' notion that maps to days, adding essentially nothing beyond the schema — the baseline 3 for full coverage.

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?

Names the specific resource (Amazon Advertising performance for the connected account) and enumerates the exact metrics returned (spend, sales, clicks, orders, ACoS, ROAS) plus the connection-status check. It also explicitly distinguishes itself from the profit tools, so an agent can separate it from get_profit_summary without opening either 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?

Gives a clear triggering condition — 'call this as well when a question is about total profitability' — and implies the connection-existence check as a first step. It stops short of naming a specific sibling alternative or stating explicit exclusions, so it is strong but not fully routing.

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