Assign vertices to a named vertex group with a chosen weight, enabling precise control over deformation and influence on a target object.
Assign vertices to a vertex group with a specific weight.
Args: object_name: Target object. group_name: Vertex group name. vertices: Vertex indices to assign. weight: Weight value (0.0 - 1.0).
| Name | Required | Description | Default |
|---|---|---|---|
| weight | No | ||
| vertices | Yes | ||
| group_name | Yes | ||
| object_name | Yes |
Changes observed during successful MCP inspections.
v3.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full behavioral burden. It explains what the tool does at a high level but does not disclose side effects, such as whether existing vertex weights are overwritten, whether the target object must be a mesh, or what happens if the vertex group does not exist.
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 compact and front-loaded: a one-sentence summary of the operation followed by a labeled argument list. Every line adds necessary information, and there is no redundant or speculative content.
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?
All parameters are described, making the tool minimally callable, but the description omits important operational context for an annotationless mutation tool: prerequisites, effects on existing assignments, possible failure modes, and return behavior. It is adequate but not fully 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?
Schema description coverage is 0%, so the Args section is the only semantic source. It meaningfully explains all four parameters: object_name is the target object, group_name names the vertex group, vertices are vertex indices, and weight is explicitly constrained to 0.0-1.0. This fully compensates for the schema's lack of descriptions.
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 states a specific action ('Assign vertices to a vertex group') with a clear resource and an additional scoping detail ('with a specific weight'). It is immediately distinguishable from sibling tools like create_vertex_group or assign_material, which target different resources or operations.
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 when-to-use guidance is provided. The description does not mention whether the vertex group must already exist, whether this tool is the right choice only after create_vertex_group, or when an alternative would be preferable. The agent must infer usage purely from the name and operation.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.