create_pmax_campaign

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

With no annotations, the description fully carries the burden. It discloses that the campaign is created paused, defaults for time_zone, aborts the asset-group add if the campaign add fails, returns a draft, and details mid-apply failure behavior with landed IDs. It also includes live-verification status for different paths, adding significant behavioral context beyond any structured metadata.

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 long but well-structured and front-loaded with the core purpose. It progresses logically from defaults to rules, verification notes, and failure handling. Every sentence adds important context, so it is appropriately detailed rather than unnecessarily verbose.

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?

Given 10 parameters, 0% schema coverage, no annotations, and no output schema, the description is remarkably complete. It covers prerequisites (images, target CPA), defaults, failure semantics, retry guidance, and even the apply step. An agent has enough information to use the tool correctly and avoid common pitfalls.

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 compensate. It explains time_zone default, target_cpa requirement (including the setting to allow null), and image_media_ids constraints (must exist in media library, specific MediaTypes, unknown types raise). It does not explicitly describe headlines, long_headlines, descriptions, or business_name, but these are self-explanatory. Overall, it adds meaningful meaning for the most complex parameters.

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 drafts a Performance Max campaign plus its first asset group, created paused. This is a specific verb+resource that distinguishes it from siblings like draft_campaign, draft_responsive_search_ad, etc., even without naming them.

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?

Provides concrete usage context: target_cpa is required by default and how to enable a no-target path via settings; images are mandatory and must meet media library type requirements. It also explains failure handling and retry semantics. However, it does not explicitly mention alternative tools or when to use a different draft function, so a small gap remains.

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