Create card

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

Annotations are minimal (readOnlyHint=false, openWorldHint=true), so the description carries the burden of behavioral disclosure. It adds that the tool returns card_uri and includes critical warnings: 'If the intended creative failed to upload or process, STOP. Do not promote a still, a source image, or a pre-existing library asset.' These disclose mutation side effects and safety constraints beyond what annotations provide, though it does not detail permissions or rate limits.

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 compact and front-loaded: it states the core purpose and return value first, then provides component examples and safety warnings. Every sentence adds value, with no redundancy or fluff. The structure is logical, making it easy for an agent to parse the essential information quickly.

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 tool with a complex array parameter and no output schema, the description covers a lot: purpose, return value, component structure examples for three card types, and warnings about failure. It does not explain the 'name' parameter or mention prerequisites like uploading media first, but given the available annotations and schema, it is largely complete and provides enough context for an agent to invoke the tool 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 only 33% (only account_id is described). The description adds meaning for the 'components' parameter through concrete examples of valid structures (e.g., MEDIA, DETAILS, BUTTON, SWIPEABLE_MEDIA), but it does not explain the 'name' parameter at all. Given the low coverage, the description partially compensates but leaves gaps for parameter meaning.

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's purpose: 'Create an ad card from raw components' and specifies the return value 'Returns card_uri.' It provides concrete examples of component structures (MEDIA, DETAILS, BUTTON, SWIPEABLE_MEDIA) that distinguish card types, making the tool's function specific and distinct from siblings like x_ads_create_image_ad or x_ads_create_video_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?

The description gives guidance on which component types to use for website, app, and carousel cards, but it does not explicitly state when to use this tool versus alternatives like x_ads_create_image_ad or x_ads_create_video_ad. There is no 'when not to use' or contrast with sibling tools, so usage selection is only implied by the tool name and purpose.

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