get_pmax_placement_performance

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

Annotations already mark this as readOnlyHint=true and openWorldHint=true, so the safety profile is clear. The description adds useful behavioral context by specifying the breakdown dimensions and confirming the acceptable date_range format, which goes 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 compact and front-loaded with the tool's purpose, followed by a minimal parameter list. Every sentence earns its place, and there is no redundant filler or repetition of schema defaults.

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 simple read-only report tool with three string parameters and no output schema, the description covers the core invocation requirements: required IDs and the date range format. It could go further by naming the returned metrics, but the listed placement breakdown gives sufficient operational context.

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%, so the description must explain the parameters, and it does: customer_id, campaign_id, and date_range are each given a brief semantic definition. It also clarifies that date_range accepts either predefined values or a comma-separated explicit range, compensating well for the schema's missing descriptions.

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 begins with a specific verb and resource: 'Get PMax placement performance breakdown' and enumerates the placement channels (Search, YouTube, Display, Discover, Gmail). This clearly distinguishes it from sibling performance tools like get_campaign_performance or get_asset_performance by naming the unique PMax placement dimension.

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 PMax placement breakdowns but does not explicitly state when to choose it over related siblings such as get_campaign_performance or get_ad_group_performance. There is enough context for an agent to infer the intended use, but no explicit exclusions or alternative routing.

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