blender-mcp

by kleer001

Overview Schema Source Related Servers Discussions Admin

Python

Local

create_geonodes_modifier

Apply a geometry nodes modifier to an object in Blender, creating a new node tree or using an existing one.

Instructions

Add a geometry nodes modifier. Creates a new tree or uses an existing one.

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": "<object>"
    },
    "name": "create_geonodes_modifier"
  }
}

Input Schema

Name	Required	Default
`name`	No	GeometryNodes
`object`	Yes
`tree_name`	No

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Aug 10, 2026

TDQS

C2.7/5.0

Behavior2/5

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

With no annotations provided, the description carries the full burden of disclosing side effects and behavior. It only states that a new tree is created or an existing one is used, but does not mention how multiple modifiers are handled, whether existing modifiers are affected, or any prerequisites. This is a significant gap for a tool that mutates an object's modifier stack.

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 extremely concise, consisting of a single sentence with no filler. It front-loads the core action and immediately adds a key behavioral detail. However, it may be under-specified, which prevents a perfect score, but it earns credit for being economic.

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

Completeness2/5

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

For a tool with three parameters, no annotations, and only a minimal description, context is incomplete. The output schema exists but doesn't provide usage context. The description fails to cover prerequisites, parameter relationships, or expected outcomes, making it insufficient for reliable tool invocation.

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

Parameters2/5

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 vaguely relates to the tree_name parameter by mentioning new/existing trees, but it does not explain the meaning of 'name' or 'object'. The description adds minimal value over the raw schema, leaving parameter meanings unclear.

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 function: 'Add a geometry nodes modifier.' It also specifies a key differentiator from generic modifier tools by mentioning 'Creates a new tree or uses an existing one.' While it doesn't explicitly name sibling tools, the resource and scope are specific enough to distinguish it from add_modifier and create_geonode.

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 provided on when to use this tool versus alternatives like add_modifier or create_geonode. There are no explicit context cues, prerequisites, or exclusions. The description only implies usage for adding a geometry nodes modifier, which is insufficient given the sibling tools.

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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