blender_set_material

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

The description discloses key behavioral traits beyond annotations: 'Creates or updates a material', 'Assigns it to the first material slot', and 'using Principled BSDF'. This adds valuable context beyond the annotations' idempotentHint and readOnlyHint. No contradiction found.

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 well-structured and concise: a clear opening sentence, followed by organized Args, Returns, and Example sections. No unnecessary verbosity, and the example helps clarify usage.

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 focused material-setting tool, the description covers purpose, inputs, output, and usage example. It does not discuss alternatives or edge cases (e.g., objects without material slots), but these are likely minor. Given the output schema exists and annotations are present, the description is sufficiently complete.

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 input schema contains detailed descriptions for every parameter (color, metallic, roughness, object_name, material_name, emission_color, emission_strength), so the description need not repeat them. The description does summarize the main parameters ('base color, metallic, roughness, and optional emission') but adds little beyond the schema. Baseline 3 is appropriate given high schema coverage.

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 'Apply a PBR material to an object using Principled BSDF' with specific verb+resource+method. It distinguishes from sibling tools by being the only material-specific operation, and includes details on creation/update and assignment behavior.

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?

Usage is implied: it is the tool for applying materials. However, no explicit 'when to use vs alternatives' is provided, especially relative to blender_execute_python which could also manipulate materials. There are no exclusions or stated scenarios.

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