unity_script_update

THE RISK

Medium Risk

Why unity_script_update needs a policy

This tool modifies script files reversibly (existing C# scripts can be edited, versions controlled, or reverted). While it doesn't delete data, it can change critical game logic, asset references, and application behavior. The high severity reflects the potential for an AI agent to inadvertently corrupt game logic, break dependencies, or introduce security vulnerabilities in production code.

From the tool's definition Tool name 'unity_script_update' and description 'Update the contents of an existing C# script file' directly indicate modification of existing code files.

Documented attack patterns abuse exactly the kind of access unity_script_update gives an agent:

POLICY

How to control unity_script_update

PolicyLayer is an MCP gateway — it sits between your AI agents and Unity MCP Server, and nothing reaches the server without passing your rules. This is the rule we recommend for unity_script_update:

policy.json

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

unity_script_update 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.

Create a free account and register Unity MCP Server — nothing to install.
Add this policy — paste it, or build it visually.
Point your MCP client (Claude, Cursor, anything) at your gateway URL.

LIMIT THIS TOOL →

Free to start. No card required.

EXPLORE

Related tools and policies

More Unity MCP Server tools

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Go deeper

The MCP Attack Database → Documented attack patterns against MCP deployments — and the policies that stop them.
Argument validation → Checking tool call arguments against schema and policy before they run.
Scoped token → Per-person credentials that grant a defined subset of servers and tools.
Rate Limiting MCP Tool Calls: A Practical Guide →
MCP Security: Why Prompt Guardrails Aren't Enough →

FAQ

Questions about unity_script_update

What does the unity_script_update tool do? +

Update the contents of an existing C# script file. It is categorised as a Write tool in the Unity MCP Server MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.

How do I enforce a policy on unity_script_update? +

Register the Unity MCP Server MCP server in PolicyLayer and add a rule for unity_script_update: 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 Unity MCP Server. Nothing to install.

What risk level is unity_script_update? +

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

Can I rate-limit unity_script_update? +

Yes. Add a rate_limit block to the unity_script_update 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 unity_script_update completely? +

Set action: deny in the PolicyLayer policy for unity_script_update. 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 unity_script_update? +

unity_script_update is provided by the Unity MCP Server MCP server (anklebreaker-studio/unity-mcp-server). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.

Enforce policy on every Unity MCP Server tool call.

Start from Unity MCP Server, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.

CHECK YOUR STACK →