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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description adds useful behavioral context: results are sorted by spend, and the specific metrics returned are enumerated. This goes beyond what the annotations alone convey without contradicting them.

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 compact and front-loaded with the core purpose, then efficiently lists the returned metrics and supported filter dimensions. Every sentence contributes useful information with no filler or repetition of the title.

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 19-parameter tool with no output schema, the description lists the return metrics and main filters, but it omits important invocation context such as date-range handling, pagination behavior, and how SKU/ASIN/parent scoping filters interact. The undocumented date parameters are not addressed in the description.

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 84%, so the schema already documents most parameters. The description summarizes filter categories but does not add meaningful detail beyond the schema, and it does not compensate for the undocumented date parameters (start_date, end_date, period_days).

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 specific resource ('ad group performance data within campaigns') and the action ('Query'), and lists the returned metrics and sorting behavior. It doesn't explicitly differentiate from sibling PPC tools by name, but the scope is specific enough to distinguish it from campaign-level or keyword-level tools.

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 implies the tool is for ad-group-level performance queries and mentions supported filters, but it provides no explicit guidance on when to choose this over siblings like ppc_campaigns, ppc_campaign_details, or ppc_keywords. No exclusions or alternative routing are given.

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