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

Annotations already declare read-only, open-world, non-destructive behavior, so the description's added context is useful: it warns that missing evidence appears as nulls, that provider observations/estimates are not actual account performance, and that no additional fallback calls are made. These are meaningful operational caveats beyond the structured 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 short and front-loads the domain and output type, with each sentence contributing a caveat or constraint. Some phrasing is cryptic, especially 'under a separate daily advertising budget,' but there is little 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?

With four required parameters, no schema descriptions, and no output schema, the description should do more to explain inputs and expected return shape. It mentions audience ranges and null preservation, but omits the meaning of most parameters and the exact form of the estimate.

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 0% for four required parameters, so the description carries the full burden of explaining inputs. It only indirectly references 'daily advertising budget' and does not clarify ageBands, gender, or bidUsd, leaving most parameter meaning undocumented.

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 identifies a Bing audience-estimate resource with monthly aggregate ranges and a daily budget constraint, but it lacks a clear action verb and the phrase 'under a separate daily advertising budget' is ambiguous. It does not distinguish this tool from nearby siblings such as keyword ad traffic forecasting or ad transparency search.

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?

The description gives no explicit guidance on when to use this tool versus alternatives, nor does it state prerequisites or exclusions. 'No additional calls or fallback' is a behavioral constraint rather than usage direction.

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