AI agents use set_visibility to create or update resources in Threlte — usually the action step of a workflow, after the agent has gathered context. Every call changes real data in your Threlte environment.
This tool modifies the visibility state of 3D scene objects, which is a reversible write operation. It does not execute code, delete data irreversibly, or cause financial impact. The blast radius is low since toggling visibility is easily undone and does not corrupt or permanently alter scene data.
From the tool's definition Tool name 'set_visibility' with description 'Show or hide an object' indicates modification of object properties (visibility state) that is reversible.
Documented attack patterns abuse exactly the kind of access set_visibility gives an agent:
PolicyLayer is an MCP gateway — it sits between your AI agents and Threlte, and nothing reaches the server without passing your rules. This is the rule we recommend for set_visibility:
{
"version": "1",
"default": "deny",
"tools": {
"set_visibility": {
"limits": [
{
"counter": "set_visibility_rate",
"window": "minute",
"max": 30,
"scope": "grant"
}
]
}
}
}set_visibility 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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Show or hide an object. It is categorised as a Write tool in the Threlte MCP Server, which means it can create or modify data. Consider rate limits to prevent runaway writes.
Register the Threlte MCP server in PolicyLayer and add a rule for set_visibility: 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 Threlte. Nothing to install.
set_visibility 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 set_visibility 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 set_visibility. 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.
set_visibility is provided by the Threlte MCP server (serifeusstudio/threlte-mcp). PolicyLayer sits as a proxy in front of this server to enforce policies before tool calls reach the server.
Start from Threlte, add the rest of your stack, and see everything your agents can call. Then put policy on all of it.
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30 Threlte tools catalogued and risk-classified — across an index of 43,000+ MCP servers.