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

Annotations already declare this as a destructive, open-world, idempotent, non-read-only operation. The description adds useful billing and retry context ('existing subscription,' 'maximum credit cost,' reuse requestId), but it does not explain the destructiveHint or clarify whether generation is synchronous or asynchronous.

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 two sentences, front-loaded with the core action and followed by critical invocation constraints. There is no filler, and the retry warning is placed where an agent will see it before calling.

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 complex 7-parameter image-generation tool with no output schema and no schema descriptions, the description is missing too much: most parameters are unexplained, the asynchronous job relationship is not stated, and expected return or job-tracking behavior is absent.

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?

With 0% schema description coverage across 7 parameters, the description must carry parameter meaning. It only explains requestId and maxCredits in any detail, leaving prompt, ratio, resolution, sourceId, and referenceIds undocumented beyond their types and enums.

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: 'Generate one image.' It also scopes the operation to an 'existing subscription.' However, it does not explicitly differentiate this tool from siblings such as get_image_job or list_image_jobs, so it falls short of a 5.

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 important retry guidance for requestId after network errors and warns against resubmitting unknown jobs with a new ID. It does not explain when to use this tool versus get_image_job, list_image_jobs, or other sibling tools, leaving usage context largely implied.

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