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Blender MCP Ultra

Blender MCP Ultra

by 3bdull4h2008
OverviewSchemaSourceRelated ServersDiscussionsAdmin
Python
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add_object_constraint

Apply object constraints in Blender, such as copy location, rotation, limit, or track-to. Define target, sub-target, and custom settings to control object behavior.

Instructions

Add a constraint to an object.

Common types: COPY_LOCATION, COPY_ROTATION, COPY_SCALE, TRACK_TO, FOLLOW_PATH, CHILD_OF, LIMIT_LOCATION, LIMIT_ROTATION, LIMIT_SCALE, TRANSFORM, CLAMP_TO, DAMPED_TRACK_TO, IK, PUSH_PULL,Stretch To.

Args: object_name: Target object. constraint_type: Constraint type (e.g. 'COPY_LOCATION'). name: Custom name for the constraint. target_name: Target object for the constraint. subtarget: Sub-target (bone name for armature targets). settings: Dict of constraint properties to set.

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>",
      "constraint_type": "<constraint_type>"
    },
    "name": "add_object_constraint"
  }
}

Input Schema

NameRequiredDescriptionDefault
nameNo
settingsNo
subtargetNo
object_nameYes
target_nameNo
constraint_typeYes

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 present, so the description is the sole source of behavioral information; it conveys the operation type but discloses no side effects, constraint-stack behavior, required target relationships, or error conditions. Since this is a mutating tool, more behavioral context is needed beyond 'Add a constraint'.

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 well-structured with a purpose sentence, a useful type list, and a labeled Args block; there is no filler. It is a bit long, but each line earns its place by documenting a parameter.

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 six-parameter mutation with no annotations and no output schema, the description gives a workable but incomplete picture: it omits which constraint types require target_name/subtarget, how settings values map to Blender properties, and any validation behavior. It is enough for a simple call but not for reliable advanced use.

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 coverage is 0%, so the Args list is essential; it adds meaning for all six parameters, especially subtarget ('bone name for armature targets') and the enumerated constraint types. However target_name is only restated as 'Target object', and allowed settings keys/property names are left unspecified.

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

Purpose5/5

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

The first sentence states the exact operation ('Add a constraint to an object') and the list of common constraint types gives concrete scope. Combined with the object_name parameter, this clearly distinguishes it from sibling add_bone_constraint and other constraint-related tools.

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

Usage Guidelines2/5

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

No guidance is given on when to use this tool over add_bone_constraint, remove_object_constraint, setup_ik_chain, or other constraint tools. The description implies usage for object constraints but never states exclusions or alternative routing.

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

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