set_units

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

Annotations indicate destructiveHint=true, implying the tool modifies scene state. The description adds the critical warning about export size errors, which is beyond the annotation. It does not detail what exactly gets changed (e.g., existing objects), but the warning covers the main risk.

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 compact, with the crucial warning front-loaded and a bilingual (Chinese/English) format that is accessible. Both language sections are equally concise and informative, with no fluff.

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?

The description fully covers the tool's purpose, setup importance, and consequence of misalignment. It does not describe the exact parameter effects or return values, but the absence of an output schema and the simplicity of the tool make it sufficient for correct 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?

The schema covers all three parameters with descriptions and enums. The description adds no additional parameter semantics beyond reiterating the scale factor and the consequences. Since schema coverage is 100%, baseline 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?

The description clearly states the tool sets the scene unit system and display units, using a specific verb-resource pair. It distinguishes itself from related tools like get_units and set_time_config by focusing on scene units specifically.

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 explicitly instructs to align units with the target engine/project before modelling, warning of severe consequences (100x size error) otherwise. This provides clear when-to-use guidance and preconditions, which is crucial for a setup tool.

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