Create image ad (pipeline)

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

Goes well beyond the readOnlyHint=false annotation by disclosing the full pipeline order, active-status precondition, and failure safety rules. This is rich behavioral context that the annotations alone could not provide.

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?

Three dense sentences with no filler. The pipeline is front-loaded, followed by input requirements and guardrails; every sentence adds operational value.

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?

Strong for a complex composite tool with no output schema: it covers pipeline, preconditions, input modes, and failure handling. Minor gaps remain around the meaning of line_item_id and what the response contains, but the agent has enough to invoke it correctly in most cases.

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 only 14%, so the description compensates by explaining media_url vs inline image, required text and destination_url, and the existing ad group target. It does not fully describe the nested image object structure or clarify that line_item_id is the ad group id, but the key input choice is clearly conveyed.

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 composite action: upload creative, create website card, create nullcast post, and promote onto an existing ad group. This clearly distinguishes it from sibling tools like x_ads_create_video_ad and x_ads_create_ad.

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 clear context and preconditions: requires an existing ad group, active campaign and ad group, media_url or inline image, and specified required fields. Strong when-not guidance on stopping if the creative failed or promoting a stale asset, though it does not name alternative tools explicitly.

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