Skip to main content
Glama
Sign In
Blender MCP Ultra

Blender MCP Ultra

by 3bdull4h2008
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
Local

set_shape_key_value

Set the morph value of a shape key on a mesh object to control its deformation. Specify object, key, and value from 0.0 to 1.0.

Instructions

Set the value of a shape key to control morphing.

Args: object_name: Target mesh object. key_name: Name of the shape key. value: Morph value (0.0 = base, 1.0 = full morph).

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "object_name": "<object_name>",
      "key_name": "<key_name>"
    },
    "name": "set_shape_key_value"
  }
}

Input Schema

NameRequiredDescriptionDefault
valueNo
key_nameYes
object_nameYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv3.0.0

TDQS

B3.2/5.0
Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. The description explains the value range semantics but doesn't disclose what happens if the shape key doesn't exist, whether the operation is destructive/reversible, or whether it requires the object to be a mesh. It also doesn't mention if the change is immediately visible or requires a viewport update.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is compact and front-loaded with the core purpose. The Args section is minimal and each line earns its place. The value semantics explanation is useful and not redundant with the schema. It could be slightly more structured but is appropriately sized for a simple setter tool.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple setter tool with 3 parameters and no output schema, the description covers the essential purpose and value semantics. However, it lacks context about error conditions (e.g., missing shape key), whether the object must be a mesh, and how this relates to the animation workflow. Given the tool's simplicity, this is adequate but not complete.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must compensate. It does explain the 'value' parameter's semantics (0.0 = base, 1.0 = full morph), which adds meaning beyond the schema. However, it only restates the names of object_name and key_name without adding context about what constitutes a valid key_name or how to find it. The description partially compensates but leaves gaps.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose: 'Set the value of a shape key to control morphing.' This is a specific verb+resource combination that distinguishes it from siblings like add_shape_key and remove_shape_key. However, it doesn't explicitly differentiate from other shape-key-related tools or mention that it operates on mesh objects, which is implied by the parameter description.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage context by explaining the morph value semantics (0.0 = base, 1.0 = full morph), which helps an agent understand when to use this tool. However, it doesn't explicitly state when to use this tool versus alternatives like add_shape_key or set_shader_node_value, nor does it mention prerequisites like the object needing to have a shape key already.

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

Deploy Server

Other Tools