enter_playmode · Unity MCP: Risk & Policy

WHAT IT DOES

What enter_playmode does on Unity MCP

AI agents invoke enter_playmode to trigger actions in Unity MCP. What it does depends on the arguments the agent supplies, and its effects often reach beyond the immediate call — builds kicked off, notifications sent, workflows started.

WHY IT NEEDS A POLICY

Why enter_playmode needs a policy

Entering Play Mode triggers Unity's game runtime execution environment, running game code, scripts, and simulations. This is an Execute-category action as it starts active execution of game logic. Misuse could interfere with editor state or ongoing work, though effects are generally reversible via exit_playmode.

From the tool's definition Enter Unity Play Mode for testing gameplay

Attacks that exploit this kind of access

Recommended rule Ready

Verdict

enter_playmode Rate-limited

enter_playmode stays usable, but rate-capped — a runaway agent can't fire it dozens of times a minute. Everything else on the server is denied unless you say otherwise.

View as policy code

policy.json

{
  "version": "1",
  "default": "deny",
  "tools": {
    "enter_playmode": {
      "limits": [
        {
          "counter": "enter_playmode_rate",
          "window": "minute",
          "max": 10,
          "scope": "grant"
        }
      ]
    }
  }
}

RATE-LIMIT THIS TOOL →

Instant setup, no code required.

PolicyLayer is an MCP gateway: every tool call is checked against your rule before it reaches Unity MCP, so you can run agents against it safely.

FAQ

Questions about enter_playmode

What does the enter_playmode tool do? +

Enter Unity Play Mode for testing gameplay. Can optionally pause on enter. It is categorised as a Execute tool in the Unity MCP MCP Server, which means it can trigger actions or run processes. Use rate limits and argument validation.

How do I enforce a policy on enter_playmode? +

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

What risk level is enter_playmode? +

enter_playmode is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.

Can I rate-limit enter_playmode? +

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

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

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