set_material_instance_vector

Set a vector parameter on a material instance.

SERVERUnreal SOURCE@jjpxdev/unreal-mcp

Medium RISK CLASS

Category Write

Parameters 33 required

Recommended Rate-limitedsee the rule below

Registry record Grade F, identity unverified Pull the record →

This record as markdown: /tools/jjpxdev-unreal-mcp/set-material-instance-vector.md

WHAT IT DOES

What set_material_instance_vector does on Unreal

AI agents use set_material_instance_vector to create or update resources in Unreal, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Unreal environment.

Parameter	Type	Required	Description
`value`	object	Yes	RGBA values (0-1)
`instance_path`	string	Yes	Material instance asset path
`parameter_name`	string	Yes	Vector parameter name

Parameters from the server's own tool schema.

RISK

Why set_material_instance_vector is rated Medium

This tool modifies material instance parameters, which is a reversible write operation. The change can be undone by setting the parameter to a different value. While it affects visual rendering in Unreal Engine, the modification is not destructive and can be easily reverted.

From the tool's definition Tool name is 'set_material_instance_vector' and description states 'Set a vector parameter on a material instance.' The verb 'set' indicates modification of an existing resource (a material instance parameter) in a reversible manner.

Attacks that exploit this kind of access

RECOMMENDED RULE

The rule that runs set_material_instance_vector safely

PolicyLayer is an MCP gateway: it sits between your AI agents and Unreal, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For set_material_instance_vector, this is the rule to start with:

set_material_instance_vector Rate-limited

set_material_instance_vector stays usable, but capped: an agent stuck in a loop can't make hundreds of changes a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "set_material_instance_vector": {
      "limits": [
        {
          "counter": "set_material_instance_vector_rate",
          "window": "minute",
          "max": 30,
          "scope": "grant"
        }
      ]
    }
  }
}

LIMIT THIS TOOL → Instant setup, no code required.

The button opens the PolicyLayer dashboard: create your workspace, connect Unreal, apply this rule, and every set_material_instance_vector call is checked against it from then on.

FAQ

Questions about set_material_instance_vector

What does the set_material_instance_vector tool do? +

Set a vector parameter on a material instance. It is categorised as a Write tool in the Unreal MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

What parameters does set_material_instance_vector accept? +

set_material_instance_vector accepts 3 parameters: value, instance_path, parameter_name. Required: value, instance_path, parameter_name. The full parameter table on this page comes from the server's own tool schema.

How do I enforce a policy on set_material_instance_vector? +

Register the Unreal MCP server in PolicyLayer and add a rule for set_material_instance_vector: allow, deny, rate-limit, or require approval. Point your MCP client at the PolicyLayer proxy URL and the rule is enforced on every call, before it reaches Unreal. Nothing to install.

What risk level is set_material_instance_vector? +

set_material_instance_vector is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.

Can I rate-limit set_material_instance_vector? +

Yes. Add a rate_limit block to the set_material_instance_vector rule in your PolicyLayer policy. For example, setting max: 10 and window: 60 limits the tool to 10 calls per minute. Rate limits are tracked per agent session and reset automatically.

How do I block set_material_instance_vector completely? +

Set action: deny in the PolicyLayer policy for set_material_instance_vector. The AI agent will receive a policy violation error and cannot call the tool. You can also include a reason field to explain why the tool is blocked.

What MCP server provides set_material_instance_vector? +

set_material_instance_vector is provided by the Unreal MCP server (@jjpxdev/unreal-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

KEEP EXPLORING

More on Unreal, and thousands of servers like it.

This server

All 127 Unreal tools →

Across the catalogue

emit_assumption_set on 0sec →set-prioity on Kanban MCP Server → The MCP Attack Database →

Guides

Govern customer-ops agents →Argument validation →Scoped token →