set_material_parameter

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

Annotations already declare mutating, non-readOnly, non-destructive, but the description adds non-obvious behavior: sRGB hex values are auto-converted to linear, alpha is preserved, and modifying a shared original affects multiple parts. It doesn't cover error/failure behavior (invalid parameter names, wrong node), which keeps it at 4 rather than 5.

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?

Front-loaded with the verb+resource, then node guidance, value formats, and cautions in a logical order. Dense with parenthetical detail, but every clause (conversion rule, matrix shape, copy warning) earns its place given zero schema coverage.

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?

Output schema exists so return values needn't be explained, and annotations cover the safety profile. Format specs, undo path, node default, and shared-material risk are all present; only the identifier semantics for material/parameter remain thin for a mutation tool.

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 0%, so the description carries the burden. It richly documents value (color linear 0-1 vs #RRGGBB sRGB conversion, alpha preservation, matrix object shape with scale/rotate/translate) and states node_id defaults to root, but material and parameter are only implicitly defined — no format or naming convention is given for them.

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?

States a specific verb and resource ('Règle un paramètre d'un nœud du matériau') and distinguishes itself from siblings by naming get_material for parameter discovery and assign_material for copies. An agent knows exactly what operation this performs versus add_material_node or connect_material_nodes.

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?

Gives explicit conditional guidance: root node by default but useful params are often on the shader node (see get_material), undoable via undo_material_changes, and on shared originals use assign_material to a copy instead. Both the when and the when-not, plus the recovery path, are spelled out.

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