mat_set_opacity

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

Annotations already flag the operation as mutating (readOnlyHint=false, destructiveHint=true). The description adds useful non-obvious behavioral context: opacity is interpreted on different scales depending on the material type, and callers must follow the target material's convention. This is exactly the kind of caveat an agent needs before invoking the tool.

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 definition is short, front-loads the purpose, and then gives the critical range caveat. The bilingual duplication slightly increases length but is reasonable for this audience; no extraneous detail is included.

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 two-parameter setter with full schema documentation and no output schema, the description covers the essential caveat (material-dependent opacity scale) and all required inputs. Missing details such as error behavior when the material does not exist are minor and not critical for a straightforward setter.

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%; both parameters are documented in the schema. The description repeats the same range information rather than adding new parameter semantics beyond the schema, so the baseline score 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?

The description clearly states a specific operation and resource: 'Set material opacity' / '设置材质不透明度'. The purpose is unambiguous among the material sibling tools, though it does not explicitly differentiate itself from generic alternatives like mat_set_property or set_property_value.

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?

No guidance is given on when to choose this tool over the generic material setters present in the sibling list (e.g., mat_set_property, set_property_value). The only condition mentioned is about the value scale (0..100 vs 0..1) for different material types, which is parameter handling rather than tool-selection guidance.

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