list_scene_classes

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the agent knows this is a safe read operation. The description adds the behavioral detail that it counts classes 'actually present' in the current scene, implying it filters to used classes rather than listing all known classes. However, it does not disclose the return format (e.g., a map of class names to counts) or whether the count includes hidden/frozen objects. With annotations covering the safety profile, a 3 is appropriate.

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 short sentences (Chinese and English) with zero waste. The core action and scope are front-loaded in both languages. Every word earns its place.

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 zero-parameter read-only tool with annotations covering safety, the description is mostly complete. The main gap is the return format: an agent might not know whether the result is a list, a dictionary, or a formatted string. However, given the tool's simplicity and the absence of an output schema, the description provides enough to invoke it correctly, though not enough to parse the result confidently.

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?

The tool has zero parameters, so the schema provides no parameter semantics to rely on. The description compensates by clarifying the scope ('current scene') and the operation ('count every class actually present'). Since there are no parameters to document, the description is sufficient for an agent to understand what inputs (none) are needed.

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 ('Count') and resource ('every class actually present in the current scene'), which clearly distinguishes it from the sibling list_max_classes (which lists all available classes in the system, not scene instances). It is slightly less explicit about whether 'class' refers to object classes or material classes, but the context of 'current scene' and the sibling list_max_classes makes the intent reasonably clear.

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 implies usage: call it when you need to know which classes are actually used in the current scene. It does not explicitly state when not to use it or mention alternatives like list_max_classes or get_class_properties. The sibling list_max_classes is a clear alternative, but the description does not name it or provide a selection rule.

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