P-MAX のアセットグループを作成

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

Annotations only give readOnly=false/destructive=false/openWorld=true, but the description adds substantive behavior: atomic all-or-nothing request rejection by Google, the 5120 KB per-image limit, the default PAUSED status, and validate_only's dry-run semantics. These are meaningful traits beyond what annotations convey.

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 purpose and the atomic-creation constraint are front-loaded, and the dense constraint list earns its place given the strict validation rules. It is long but nearly every clause carries required calling information, with only minor redundancy between description and schema.

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 15-parameter, 10-required mutation tool with no output schema, the description covers atomicity, required asset counts and ratios, character-counting rules, image size limits, validate_only pre-checks, and the default status. Nothing essential to a correct call is missing.

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 coverage is 100%, so baseline is 3, but the description adds semantics the schema lacks: images accept local file paths or http(s) URLs (not stated per-field), the full-width-counts-as-2 rule that halves Japanese character limits, and minimum/maximum counts for each asset type. These extend beyond the structured field 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 states a specific verb and resource (creating a P-MAX asset group) and explicitly disambiguates from siblings by noting P-MAX has no ad groups or ads, unlike google_ads_create_ad_group. An agent can tell exactly what this produces without opening the schema.

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 gives actionable operational guidance: run validate_only=true first to pre-check, and explains that everything must be created in a single mutate call per Google's requirement. It does not explicitly contrast with google_ads_mutate for partial updates, so usage is clear but not exhaustively scoped.

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