Vertex.Gemini.Generate Ad Copy

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

With no annotations, the description carries the full burden and does add one genuinely useful behavioral fact: the call incurs Vertex billing cost. It also hints at an internal two-step (brief construction, then Gemini call). However it omits latency, auth/scoping requirements, and whether output is deterministic, so the safety and cost profile is only partially covered.

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?

Two short sentences with the core action front-loaded and the cost caveat trailing appropriately. Very little waste, though the phrase "build a structured brief" is vague internal jargon that slightly obscures what the caller actually supplies.

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?

An output schema exists, so return values needn't be explained, and the description covers the action plus the cost trait. Given only three simple parameters and no nesting, the remaining gaps (model version, latency, cost magnitude) are minor for an agent to invoke it correctly.

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 does explain the meaning of `n` ("n ad-copy variants") and implies product/audience feed the "structured brief", but it adds no format, length, or constraint details for those two required strings, leaving the two most important inputs unelaborated.

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?

States a specific verb-and-resource pair: generate n ad-copy variants via Gemini from a structured brief. This separates it reasonably from the generic sibling vertex.gemini.generate, but the description never explicitly names that sibling as the non-ad-copy alternative, so the boundary is inferred rather than stated.

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 only guidance is the cost warning ("Incurs Vertex cost"), which nudges toward sparing use but gives no condition, prerequisite, or named alternative for choosing this over vertex.gemini.generate or vertex.imagen.generate. An agent must guess when ad-copy generation is the right call.

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