Create a new file or completely overwrite an existing file in the Unity project.
AI agents use write_file to create or update resources in Unity MCP Integration — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Unity MCP Integration environment.
This tool modifies project files reversibly through creation or overwriting. While overwriting could theoretically be undone via version control or undo, the tool itself performs Write operations, not irreversible Destructive deletions.
From the tool's definition Tool description explicitly states: "Create a new file or completely overwrite an existing file in the Unity project." The verb 'overwrite' indicates modification of existing data, and 'create a new file' indicates writing capability.
Documented attack patterns abuse exactly the kind of access write_file gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Unity MCP Integration, and nothing reaches the server without passing your rules. This is the rule we recommend for write_file:
{
"version": "1",
"default": "deny",
"tools": {
"write_file": {
"limits": [
{
"counter": "write_file_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}write_file 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.
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Create a new file or completely overwrite an existing file in the Unity project. It is categorised as a Write tool in the Unity MCP Integration MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Unity MCP Integration MCP server in PolicyLayer and add a rule for write_file: 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 Integration. Nothing to install.
write_file 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 write_file 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 write_file. 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.
write_file is provided by the Unity MCP Integration MCP server (quazaai/unitymcpintegration). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Deterministic rules across all 15 Unity MCP Integration tools. Per-identity grants. Full audit log. Live in minutes. Nothing to install.
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15 Unity MCP Integration tools catalogued and risk-classified — across an index of 42,500+ MCP servers.