AI agents invoke start_game 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.
This tool initiates execution of a Unity game environment, which is an active operation with side effects (process startup, resource allocation, state changes). It belongs in Execute rather than Write because it triggers an external program/runtime whose behavior depends on the game's code.
From the tool's definition Tool name is 'start_game' on a Unity-MCP server that 'enables AI to interact with Unity game environments.' Starting a game is an active operation that triggers external execution of a game process.
Documented attack patterns abuse exactly the kind of access start_game gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Unity-MCP, and nothing reaches the server without passing your rules. This is the rule we recommend for start_game:
{
"version": "1",
"default": "deny",
"tools": {
"start_game": {
"limits": [
{
"counter": "start_game_rate",
"window": "minute",
"max": 10,
"scope": "grant"
}
]
}
}
}start_game 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.
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start_game. 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.
Register the Unity- MCP server in PolicyLayer and add a rule for start_game: 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.
start_game is a Execute tool with high risk. Execute tools should be rate-limited and have argument validation enabled.
Yes. Add a rate_limit block to the start_game 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 start_game. 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.
start_game is provided by the Unity- MCP server (tsavo/unity-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Unity-MCP, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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7 Unity-MCP tools catalogued and risk-classified — across an index of 43,000+ MCP servers.