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

With annotations already declaring readOnlyHint=false, destructiveHint=false, and openWorldHint=false, the description adds useful context that the reply displays the image and that it is not part of the design. However, it does not explain replacement behavior, persistence, or side effects beyond what the annotations imply.

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 short and front-loads the core action and source options. The fragment 'Not in the design' is useful but slightly cryptic, keeping it from being maximally clear.

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?

Given four params, full schema descriptions, annotations, and no output schema, the description supplies the key context: what source to load, that the reply shows the image, and that it is not a design insertion. It leaves some secondary behavior such as replacement semantics unstated, but is broadly complete for invocation.

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 coverage is 100%, so the parameter meanings are already documented in the input schema. The description reinforces the candidate/data_url source distinction but adds little beyond the schema and does not mention the 'name' parameter.

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 uses a specific verb ('Load') and resource ('reference image'), and ties it to a planned illustration and find_references candidates. It also distinguishes the action from design placement via 'Not in the design,' though the phrasing is somewhat compressed.

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?

It gives clear usage context: use for a planned illustration's reference picture, either a find_references candidate or the user's own data_url image. 'Not in the design' provides an exclusion, but it does not explicitly name sibling tools such as place_image or upload_asset.

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