set_polygroup_material_id

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

Annotations already declare this as a destructive, idempotent, non-read-only write. The description adds an important behavioral caveat beyond annotations: the engine's polygroup existence check is surfaced as polygroup_id_valid, and a false value means nothing was painted even though the call succeeded.

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-loads the action and scope, then adds usage context and the critical failure-mode warning before listing return fields. The return list is useful because no output schema exists, and the description avoids redundancy or filler.

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?

Without an output schema, the description supplies the return shape, including the polygroup_id_valid and applied flags. Combined with annotations that cover safety and a schema that fully documents parameters, it gives an agent enough context to invoke and interpret the 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 description coverage is 100%, so the input schema already documents actor_name, material_id, polygroup_id, and polygroup_layer. The description reinforces the one-polygroup scope but adds no syntax or format meaning beyond what the schema provides, so the 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?

States a specific verb (Stamp), resource (MaterialID), and scope (every triangle of one polygroup), and identifies the underlying engine function. It also differentiates itself from append_mesh_primitive by explaining that append_mesh_primitive creates the PerFace polygroups this tool then paints.

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?

Makes clear this is usually the cheapest way to paint a part and ties that guidance to meshes built via append_mesh_primitive, where each appended piece is already a polygroup. It does not explicitly state when not to use it or name alternative material-id setters such as set_mesh_material_id_in_region.

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