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

The description discloses that the data covers only 'completed days' and that trends/averages appear only after their windows are complete, which is non-obvious and valuable for an agent. While annotations already indicate readOnlyHint=true and destructiveHint=false, the description adds meaningful behavioral context about data freshness that goes beyond the annotations.

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 two sentences with no fluff. It front-loads the core purpose and scope, then immediately routes to the alternative tool. Every word is purposeful and the structure is efficient.

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 zero-parameter read-only tool, the description is complete enough: it tells the agent what data to expect, the timing caveat, and provides a pointer to an alternative. An output schema is absent, but for a summary tool, return value specifics could be assumed; still, the description could mention the granularity of units or whether data is per-day or aggregate, but these are minor gaps given the simplicity.

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?

This tool has zero parameters (as per context signals), so the baseline for parameter semantics is 4. The description adds contextual meaning about the data coverage and timing, even though there are no parameters to document. No additional parameter explanation is needed because there are none.

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 clearly states the tool provides 'exact-marketplace revenue, orders and units' for 'recent completed days', which identifies a specific verb (get), resource (orders summary), and scope. It also distinguishes itself from get_sales by explicitly mentioning which tool to use for a different time window.

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 explicitly states when to use this tool (for a complete-day summary) and when not to — 'For a specific window like last 7 days, use get_sales'. This provides clear routing between siblings and an alternative, leaving no ambiguity.

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