Assign an existing material to a Blender object to control its surface appearance. Use it when you need to apply a saved material to a specific object.
Assign an existing material to an object.
| Name | Required | Description | Default |
|---|---|---|---|
| object | Yes | ||
| material | Yes |
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Changes observed during successful MCP inspections.
v0.2.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are providedhare, and the description does not disclose side effects such as replacing an object's current material, requiring the object/material to exist, or modifying the scene state. A one-line description is too thin for a mutating operation.
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 a single front-loaded sentence with no filler or redundant restatement of the tool name.
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?
Despite the tool's simplicity, the description omits identifier formats, prerequisites (both entities must exist), and effects (e.g., assignment replaces existing material). With no annotations and no parameter detail in the schema, the description is not self-sufficient for an agent.
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 only gives string names 'object' and 'material' with no descriptions. The description adds only 'existing' and does not clarify whether parameters are names, IDs, paths, or how to reference the object/material in the Blender scene.
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 uses a specific verb ('Assign') with a clear resource ('material') and target ('object'), and the qualifier 'existing' distinguishes this from material creation. It clearly separates the tool from siblings like material_create and material_set_color.
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 phrase 'existing material' implies this is for assigning already-created materials, not creating new ones, but it does not explicitly state when to prefer this over alternatives or exclude other actions. Guidance is only implied, not stated.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.