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

Annotations already declare non-readOnly, non-destructive, non-idempotent, closed-world. The description adds the latency envelope (15-60 seconds) and an explicit instruction to tell the user about the wait up front — operationally important context the annotations cannot express. It does not say whether the call blocks or returns a task handle, which is the one remaining gap.

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 tight sentences, front-loaded with the core action, then conditioning modes, then the latency warning. No filler and nothing redundant with the 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?

An output schema exists, so return values need not be described, and the description covers purpose, conditioning inputs, and the key UX behavior (long-running). It is slightly incomplete in not clarifying sync-vs-async execution or any follow-up polling/status tool, which matters given the sibling cancel_tool_execution/get_tool_execution family.

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 100%, so prompt, quality, entityIds, aspectRatio, and imageFileIds are all already documented in the schema, including the entityId/fileId sourcing guidance. The description adds no syntax or constraint detail beyond that, so the baseline of 3 is appropriate.

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 ('Generate') and resource ('an image from a text prompt'), and immediately distinguishes two operating modes (text-to-image vs. image-to-image). This separates it cleanly from generate_avatar, generate_video_clip, and prompt_to_video_clip, which an agent must otherwise disambiguate by name alone.

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 clarifies the two usage contexts (plain prompt, or conditioned on imageFileIds/entityIds for identity consistency), which is real selection guidance. It stops short of naming alternatives or stating when-not to use it (e.g. versus generate_avatar for human characters).

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