assign_material
Apply a material to a ModelRenderer on a GameObject. Optionally target a specific material slot
This record as markdown: /tools/sbox/assign-material.md
What assign_material does on Sbox
AI agents use assign_material to create or update resources in Sbox, usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Sbox environment.
Why assign_material is rated Medium
This tool modifies game engine state by assigning materials to game objects, which is a creative/building operation typical in game development. It creates or updates material assignments on objects. While it changes game state, the change is reversible (materials can be reassigned or removed). This is Write-class because it modifies data without irreversible destruction or external effects.
From the tool's definition Tool description states 'Apply a material to a ModelRenderer on a GameObject.' The verb 'Apply' indicates modification of game object properties. This is a reversible change to visual/material properties within the game engine.
Attacks that exploit this kind of access
The rule that runs assign_material safely
PolicyLayer is an MCP gateway: it sits between your AI agents and Sbox, and checks every tool call against a rule you set before the call runs. Nothing changes on the server itself. For assign_material, this is the rule to start with:
assign_material 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.
The button opens the PolicyLayer dashboard: create your workspace, connect Sbox, apply this rule, and every assign_material call is checked against it from then on.
Questions about assign_material
Apply a material to a ModelRenderer on a GameObject. Optionally target a specific material slot. It is categorised as a Write tool in the Sbox MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Sbox MCP server in PolicyLayer and add a rule for assign_material: 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 Sbox. Nothing to install.
assign_material is a Write tool with medium risk. Write tools should be rate-limited to prevent accidental bulk modifications.
Yes. Add a rate_limit block to the assign_material 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.
Set action: deny in the PolicyLayer policy for assign_material. 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.
assign_material is provided by the Sbox MCP server (sbox-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
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