Performance Max assets

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

Annotations already declare readOnlyHint=true, openWorldHint=true, destructiveHint=false, so the safety profile is covered. The description adds genuine behavioral value beyond that by listing the concrete status enums returned and by disclosing a real limitation of the Google Ads API (no BEST/GOOD/LOW labels for PMax assets), which prevents a wrong tool choice.

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 definition is front-loaded: the core action and returned fields lead, followed by the limitation and alternative. It is slightly long due to the enum recitations and a bare documentation URL, but every section carries useful information for tool selection.

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 an output schema present, the return format need not be spelled out, and the annotations cover the safety profile, so the description only needs to establish scope and boundaries. It does that well, including the closest-proxy alternative for asset quality; a note on result limits or pagination would make it fully complete.

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 100% with only two optional parameters, so the schema fully documents campaign_id and customer_id. The description adds no syntax, format, or default-behavior detail beyond what the schema already states, making the baseline 3 appropriate.

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?

Opens with a specific verb and resource ('List the assets of Performance Max campaigns') and immediately enumerates the returned fields (type, status, content). It is clearly distinguishable from adjacent PMax tools such as get_pmax_performance or get_detailed_asset_performance, which the description explicitly frames as a different concern.

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 tells the agent that per-asset performance labels are unavailable and routes it to get_detailed_asset_performance as the substitute, which is an explicit alternative with a condition. It does not, however, state an explicit 'use this tool when you need X' trigger, so the primary usage is only implied by the resource name.

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