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

Annotations already declare readOnlyHint=false, idempotentHint=false, and destructiveHint=false. The description adds no further behavioral context such as scene behavior, layering, or persistence. Since annotations cover the mutation profile, the description is neither misleading nor contradictory, but misses an opportunity to add useful details.

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 a single, clear sentence that is front-loaded and contains no extraneous words. It is appropriately concise for a straightforward add-operation tool.

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?

With six parameters, a nested position object, and no output schema, the single-sentence description is insufficient. It lacks essential context about when to use this tool, how the billboard behaves in the scene, and how it differs from sibling tools like addMarker or addLabel. The very short description leaves significant gaps for an agent to correctly select and invoke it.

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 83% (5 out of 6 parameters have descriptions), with position lacking a description. The tool description itself does not explain parameter semantics beyond what the schema provides, such as the meaning of '叠加颜色' (overlay color) or how position is interpreted. It relies on existing schema descriptions.

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 '在指定位置添加图片图标' (add image icon at specified position) clearly states the action and resource. It specifies the behavior (adding an image icon) and the location requirement, making it distinct from simple 'add' verbs. However, it does not explicitly differentiate itself from sibling tools like addMarker or addLabel, leading to potential ambiguity.

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 provides no guidance on when to use addBillboard versus alternative tools. There are no contextual cues, alternatives, exclusions, or prerequisites. The only implied usage is for adding an image icon at a position, but no distinction from similar add* tools.

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